Owncloud webinterface shows php sourcecode

When I go to http://{IP}/owncloud instead of getting the owncloud login page I get this

* @author Lukas Reschke 
 * @author Morris Jobke 
 * @author Robin Appelman 
 * @author Thomas Müller 
 * @author Vincent Petry 
 *
 * @copyright Copyright (c) 2016, ownCloud, Inc.
 * @license AGPL-3.0
 *
 * This code is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License, version 3,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License, version 3,
 * along with this program.  If not, see 
 *
 */

// Show warning if a PHP version below 5.4.0 is used, this has to happen here
// because base.php will already use 5.4 syntax.
if (version_compare(PHP_VERSION, '5.4.0') === -1) {
	echo 'This version of ownCloud requires at least PHP 5.4.0
';
	echo 'You are currently running ' . PHP_VERSION . '. Please update your PHP version.';
	return;
}

try {
	
	require_once 'lib/base.php';

	OC::handleRequest();

} catch(\OC\ServiceUnavailableException $ex) {
	\OC::$server->getLogger()->logException($ex, ['app' => 'index']);

	//show the user a detailed error page
	OC_Response::setStatus(OC_Response::STATUS_SERVICE_UNAVAILABLE);
	OC_Template::printExceptionErrorPage($ex);
} catch (\OC\HintException $ex) {
	OC_Response::setStatus(OC_Response::STATUS_SERVICE_UNAVAILABLE);
	OC_Template::printErrorPage($ex->getMessage(), $ex->getHint());
} catch (Exception $ex) {
	\OC::$server->getLogger()->logException($ex, ['app' => 'index']);

	//show the user a detailed error page
	OC_Response::setStatus(OC_Response::STATUS_INTERNAL_SERVER_ERROR);
	OC_Template::printExceptionErrorPage($ex);
} catch (Error $ex) {
	\OC::$server->getLogger()->logException($ex, ['app' => 'index']);
	OC_Response::setStatus(OC_Response::STATUS_INTERNAL_SERVER_ERROR);
	OC_Template::printExceptionErrorPage($ex);
}

It began when I upgraded owncloud. I was running 8.1, because I added the wrong repository when I installed it, so it didn't upgrade to the newest version. I then added the stable repository and did an apt-get dist-upgrade. It then said that I can't upgrade multiple major releases at one, so I uninstalled owncloud and installed 8.2, 9.0 and 9.1 one after another. And now I have that problem.

Operating system: Ubuntu Server 14.04.5
Web server: apache 2.4.23
Database: mysql
PHP version: 5.5.9

Special configuration (external storage, external authentication, reverse proxy, server-side-encryption): using LetsEncrypt

here are the last few lines of the log:

{"reqId":"7NdDmH9DR9XmvC9fV4FZ","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T10:53:33+00:00"}
{"reqId":"A3m+LoLnKil6thVqN8w0","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T10:53:33+00:00"}
{"reqId":"XnkqsnoX9XD0TxB03YeG","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T10:53:33+00:00"}
{"reqId":"Pbq4pqGq6fBbJmgUth\/N","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T10:53:33+00:00"}
{"reqId":"wP53YT8zUCi6ivNUjo2w","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T10:53:34+00:00"}
{"reqId":"pF2qNx6vI+Z95M1tEcn8","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T10:57:03+00:00"}
{"reqId":"le\/SgNXteVx5yzn4Ytys","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:20+00:00"}
{"reqId":"lSY9OwmlOpTI0wdEx7YA","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:20+00:00"}
{"reqId":"R0EUyQAbtTZJR4grIePl","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:20+00:00"}
{"reqId":"uIPNvH80ewdWgrhMZD62","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:22+00:00"}
{"reqId":"NEv\/K9x+8sGRfJ+J7ln1","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:22+00:00"}
{"reqId":"6AXcaZHvehVQIDR1My\/E","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:22+00:00"}
{"reqId":"Qw4KLkJmVqDkrEzx\/RuG","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:22+00:00"}
{"reqId":"DarRf9KNb2oPb6gw2YO3","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:22+00:00"}
{"reqId":"27duINhjCsr7yG0bpfDT","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:23+00:00"}
{"reqId":"F0D0FhVw3YOVaB504Zv8","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:23+00:00"}
{"reqId":"jXEiTTQCaRXI3\/HYF2rN","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:24+00:00"}
{"reqId":"Z+5jA4eyi18eVmmN9KsO","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:25+00:00"}
{"reqId":"DEjYTiwMYdnH2X7rUj9k","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:25+00:00"}
{"reqId":"QChoPEnPwUlyR57A91eR","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:25+00:00"}
{"reqId":"C+pfy1jNNMqjD3QitUY3","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:26+00:00"}
{"reqId":"QtxBOvTK+gYLxXo12wC5","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:26+00:00"}
{"reqId":"ZPi6sCJI\/i+Ct0D8G7zW","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:26+00:00"}
{"reqId":"dtJ9PL5DzNLRRgR3sKUS","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:26+00:00"}
{"reqId":"beDHWh1S6298hYfgiPSc","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:28+00:00"}
{"reqId":"s5vvpARVAZ8GgvzS2qBu","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:29+00:00"}
{"reqId":"4EmAtXR3u2V8ZkwqRabN","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:29+00:00"}
{"reqId":"q07qxXzP0adSjayplZaA","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:30+00:00"}
{"reqId":"EorZKzxRR7MN+mqCBbPc","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:31+00:00"}
{"reqId":"+PIPEbkrf0zp+HW9xtam","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:31+00:00"}
{"reqId":"8IPM3SaE+2A7rTTr0xyL","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:32+00:00"}
{"reqId":"fS8v6+++jFhry3Em3qp\/","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:32+00:00"}
{"reqId":"DlIsHxGKsx+0HhpLDB65","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:32+00:00"}
{"reqId":"2mwka8FokdrIIFB2jxoC","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:33+00:00"}
{"reqId":"7yDvTMJcP9G1KPhpeKLi","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:33+00:00"}
{"reqId":"4Ff+6SIRJVN\/ZLI4iD7o","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:33+00:00"}
{"reqId":"QFbXPaxDTZLBNpcm6mNy","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:33+00:00"}
{"reqId":"A0ZtV2RqZXNvjCBBMK\/K","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:33+00:00"}
{"reqId":"oqnaEfPFFHSyc6Z6LRap","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:33+00:00"}
{"reqId":"SOvb1AEfgTIz0+7tY2Ku","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:33+00:00"}
{"reqId":"B3YaQvSeF2EzNiecKIxX","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:33+00:00"}
{"reqId":"jcZVnvoPsU2VwcCIy+7s","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:33+00:00"}
{"reqId":"z7IWnzKJZ9AhLhwksQ8E","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:33+00:00"}
{"reqId":"9ZOzLflqn0JX8fPHK+xR","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:34+00:00"}
{"reqId":"BRa4db3\/3aXuydTztQpk","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:34+00:00"}
{"reqId":"L0SsHGVFzANRcNcjc\/GH","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:34+00:00"}
{"reqId":"pFvBZbjy7MxJ7EZAKZG4","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:34+00:00"}
{"reqId":"msuTVHW72iTvcGIJE0Nz","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:34+00:00"}
{"reqId":"CHo\/BIfw+fD02FJ49Xz2","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:34+00:00"}
{"reqId":"LlrCi8POh1FERTtohua3","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:34+00:00"}
{"reqId":"YJG+2Rnml870x0oZVohX","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:34+00:00"}
{"reqId":"CP0CCzFcWcuNKMlMnRlg","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:34+00:00"}
{"reqId":"uNPqEWRwPg5zwhSrEaIS","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:35+00:00"}
{"reqId":"FIDAU6ehIKHBn+mEH9+p","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:35+00:00"}
{"reqId":"hHsR9nzBDkZ4I13Zk7cO","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:35+00:00"}
{"reqId":"7h5KUp4tRwxISA5+Fdvj","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:35+00:00"}
{"reqId":"dyqHk2h20IeziqlQ\/kdb","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:35+00:00"}
{"reqId":"znVuWCInf16eGNwwC4NH","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:35+00:00"}
{"reqId":"9LOhLLC39foOfSZBALsj","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:35+00:00"}
{"reqId":"dhUeVEbeISllSoqRwSHf","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:31:45+00:00"}
{"reqId":"OQ+Jq8D4D77m1k25VSHp","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T12:32:06+00:00"}
{"reqId":"kvm8aXhTcqRRO4cqCRlJ","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T13:31:51+00:00"}
{"reqId":"t8XYzp0RCyPQ4fXxYouQ","remoteAddr":"129.217.81.180","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T13:32:16+00:00"}
{"reqId":"pPJlNTtMFOaR81vDPpAH","remoteAddr":"192.168.11.17","app":"remote","message":"App not installed: ","level":4,"time":"2016-10-18T15:54:47+00:00"}
{"reqId":"8RfYHOsidtOxU0sDw1nc","remoteAddr":"192.168.11.17","app":"index","message":"Exception: {\"Exception\":\"OC\\\\NeedsUpdateException\",\"Message\":\"\",\"Code\":0,\"Trace\":\"#0 \\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/legacy\\\/app.php(119): OC_App::loadApp('files')\\n#1 \\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/legacy\\\/util.php(135): OC_App::loadApps(Array)\\n#2 \\\/var\\\/www\\\/owncloud\\\/lib\\\/base.php(890): OC_Util::setupFS()\\n#3 \\\/var\\\/www\\\/owncloud\\\/index.php(39): OC::handleRequest()\\n#4 {main}\",\"File\":\"\\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/legacy\\\/app.php\",\"Line\":147}","level":3,"time":"2016-10-18T17:20:07+00:00","method":"GET","url":"\/owncloud\/index.php\/core\/js\/oc.js?v=438b4d3eb3a293aac91bbf7f92935ea3","user":"--"}
{"reqId":"bEjEUqQ7TaSxyAgWVCuO","remoteAddr":"192.168.11.17","app":"core","message":"starting upgrade from 8.1.9.2 to 9.1.1.3","level":0,"time":"2016-10-18T17:20:20+00:00","method":"GET","url":"\/owncloud\/core\/ajax\/update.php?requesttoken=ISciNHUeCmZ%2FARo0BRE%2FfSQ3VSw%2BfDoMXkBwYgUpJB0%3D%3AOcRrDHsRMBncStlDGc3MKEiM6o6SPemD80Mau5OQ%2B%2FA%3D","user":"--"}
{"reqId":"bEjEUqQ7TaSxyAgWVCuO","remoteAddr":"192.168.11.17","app":"core","message":"Exception: {\"Exception\":\"Exception\",\"Message\":\"Updates between multiple major versions and downgrades are unsupported.\",\"Code\":0,\"Trace\":\"#0 \\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/Updater.php(150): OC\\\\Updater->doUpgrade('9.1.1.3', '8.1.9.2')\\n#1 \\\/var\\\/www\\\/owncloud\\\/core\\\/ajax\\\/update.php(193): OC\\\\Updater->upgrade()\\n#2 {main}\",\"File\":\"\\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/Updater.php\",\"Line\":210}","level":3,"time":"2016-10-18T17:20:20+00:00","method":"GET","url":"\/owncloud\/core\/ajax\/update.php?requesttoken=ISciNHUeCmZ%2FARo0BRE%2FfSQ3VSw%2BfDoMXkBwYgUpJB0%3D%3AOcRrDHsRMBncStlDGc3MKEiM6o6SPemD80Mau5OQ%2B%2FA%3D","user":"--"}
{"reqId":"gaubIEpMUSYRhmqTzl7d","remoteAddr":"192.168.11.17","app":"index","message":"Exception: {\"Exception\":\"OC\\\\NeedsUpdateException\",\"Message\":\"\",\"Code\":0,\"Trace\":\"#0 \\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/legacy\\\/app.php(119): OC_App::loadApp('files')\\n#1 \\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/legacy\\\/util.php(135): OC_App::loadApps(Array)\\n#2 \\\/var\\\/www\\\/owncloud\\\/lib\\\/base.php(890): OC_Util::setupFS()\\n#3 \\\/var\\\/www\\\/owncloud\\\/index.php(39): OC::handleRequest()\\n#4 {main}\",\"File\":\"\\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/legacy\\\/app.php\",\"Line\":147}","level":3,"time":"2016-10-18T17:20:45+00:00","method":"GET","url":"\/owncloud\/index.php\/core\/js\/oc.js?v=438b4d3eb3a293aac91bbf7f92935ea3","user":"--"}
{"reqId":"5HWRk3Vt5eg0gDOX1q1M","remoteAddr":"","app":"core","message":"starting upgrade from 8.1.9.2 to 9.1.1.3","level":0,"time":"2016-10-18T17:21:46+00:00","method":"--","url":"--","user":"--"}
{"reqId":"5HWRk3Vt5eg0gDOX1q1M","remoteAddr":"","app":"core","message":"Exception: {\"Exception\":\"Exception\",\"Message\":\"Updates between multiple major versions and downgrades are unsupported.\",\"Code\":0,\"Trace\":\"#0 \\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/Updater.php(150): OC\\\\Updater->doUpgrade('9.1.1.3', '8.1.9.2')\\n#1 \\\/var\\\/www\\\/owncloud\\\/core\\\/Command\\\/Upgrade.php(290): OC\\\\Updater->upgrade()\\n#2 \\\/var\\\/www\\\/owncloud\\\/3rdparty\\\/symfony\\\/console\\\/Command\\\/Command.php(259): OC\\\\Core\\\\Command\\\\Upgrade->execute(Object(Symfony\\\\Component\\\\Console\\\\Input\\\\ArgvInput), Object(Symfony\\\\Component\\\\Console\\\\Output\\\\ConsoleOutput))\\n#3 \\\/var\\\/www\\\/owncloud\\\/3rdparty\\\/symfony\\\/console\\\/Application.php(844): Symfony\\\\Component\\\\Console\\\\Command\\\\Command->run(Object(Symfony\\\\Component\\\\Console\\\\Input\\\\ArgvInput), Object(Symfony\\\\Component\\\\Console\\\\Output\\\\ConsoleOutput))\\n#4 \\\/var\\\/www\\\/owncloud\\\/3rdparty\\\/symfony\\\/console\\\/Application.php(192): Symfony\\\\Component\\\\Console\\\\Application->doRunCommand(Object(OC\\\\Core\\\\Command\\\\Upgrade), Object(Symfony\\\\Component\\\\Console\\\\Input\\\\ArgvInput), Object(Symfony\\\\Component\\\\Console\\\\Output\\\\ConsoleOutput))\\n#5 \\\/var\\\/www\\\/owncloud\\\/3rdparty\\\/symfony\\\/console\\\/Application.php(123): Symfony\\\\Component\\\\Console\\\\Application->doRun(Object(Symfony\\\\Component\\\\Console\\\\Input\\\\ArgvInput), Object(Symfony\\\\Component\\\\Console\\\\Output\\\\ConsoleOutput))\\n#6 \\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/Console\\\/Application.php(146): Symfony\\\\Component\\\\Console\\\\Application->run(NULL, NULL)\\n#7 \\\/var\\\/www\\\/owncloud\\\/console.php(94): OC\\\\Console\\\\Application->run()\\n#8 \\\/var\\\/www\\\/owncloud\\\/occ(11): require_once('\\\/var\\\/www\\\/ownclo...')\\n#9 {main}\",\"File\":\"\\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/Updater.php\",\"Line\":210}","level":3,"time":"2016-10-18T17:21:46+00:00","method":"--","url":"--","user":"--"}
{"reqId":"4v8WQvVm08JmPkqaNUfP","remoteAddr":"","app":"core","message":"starting upgrade from 8.1.9.2 to 8.2.7.1","level":0,"time":"2016-10-18T17:36:26+00:00","method":"--","url":"--"}
{"reqId":"4v8WQvVm08JmPkqaNUfP","remoteAddr":"","app":"no app in context","message":"Exception: {\"Exception\":\"Symfony\\\\Component\\\\Routing\\\\Exception\\\\RouteNotFoundException\",\"Message\":\"Unable to generate a URL for the named route \\\"calendar_index\\\" as such route does not exist.\",\"Code\":0,\"Trace\":\"#0 \\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/route\\\/router.php(325): Symfony\\\\Component\\\\Routing\\\\Generator\\\\UrlGenerator->generate('calendar_index', Array, false)\\n#1 \\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/urlgenerator.php(65): OC\\\\Route\\\\Router->generate('calendar_index', Array)\\n#2 \\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/helper.php(66): OC\\\\URLGenerator->linkToRoute('calendar_index', Array)\\n#3 \\\/var\\\/www\\\/owncloud\\\/lib\\\/public\\\/util.php(301): OC_Helper::linkToRoute('calendar_index', Array)\\n#4 \\\/var\\\/www\\\/owncloud\\\/apps\\\/calendar\\\/appinfo\\\/app.php(25): OCP\\\\Util::linkToRoute('calendar_index')\\n#5 \\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/app.php(160): require_once('\\\/var\\\/www\\\/ownclo...')\\n#6 \\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/app.php(141): OC_App::requireAppFile('calendar')\\n#7 \\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/app.php(1171): OC_App::loadApp('calendar', false)\\n#8 \\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/installer.php(222): OC_App::updateApp('calendar')\\n#9 \\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/installer.php(252): OC_Installer::updateApp(Array)\\n#10 \\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/updater.php(506): OC_Installer::updateAppByOCSId('168707')\\n#11 \\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/updater.php(320): OC\\\\Updater->upgradeAppStoreApps(Array)\\n#12 \\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/updater.php(202): OC\\\\Updater->doUpgrade('8.2.7.1', '8.1.9.2')\\n#13 \\\/var\\\/www\\\/owncloud\\\/core\\\/command\\\/upgrade.php(213): OC\\\\Updater->upgrade()\\n#14 \\\/var\\\/www\\\/owncloud\\\/3rdparty\\\/symfony\\\/console\\\/Symfony\\\/Component\\\/Console\\\/Command\\\/Command.php(253): OC\\\\Core\\\\Command\\\\Upgrade->execute(Object(Symfony\\\\Component\\\\Console\\\\Input\\\\ArgvInput), Object(Symfony\\\\Component\\\\Console\\\\Output\\\\ConsoleOutput))\\n#15 \\\/var\\\/www\\\/owncloud\\\/3rdparty\\\/symfony\\\/console\\\/Symfony\\\/Component\\\/Console\\\/Application.php(874): Symfony\\\\Component\\\\Console\\\\Command\\\\Command->run(Object(Symfony\\\\Component\\\\Console\\\\Input\\\\ArgvInput), Object(Symfony\\\\Component\\\\Console\\\\Output\\\\ConsoleOutput))\\n#16 \\\/var\\\/www\\\/owncloud\\\/3rdparty\\\/symfony\\\/console\\\/Symfony\\\/Component\\\/Console\\\/Application.php(195): Symfony\\\\Component\\\\Console\\\\Application->doRunCommand(Object(OC\\\\Core\\\\Command\\\\Upgrade), Object(Symfony\\\\Component\\\\Console\\\\Input\\\\ArgvInput), Object(Symfony\\\\Component\\\\Console\\\\Output\\\\ConsoleOutput))\\n#17 \\\/var\\\/www\\\/owncloud\\\/3rdparty\\\/symfony\\\/console\\\/Symfony\\\/Component\\\/Console\\\/Application.php(126): Symfony\\\\Component\\\\Console\\\\Application->doRun(Object(Symfony\\\\Component\\\\Console\\\\Input\\\\ArgvInput), Object(Symfony\\\\Component\\\\Console\\\\Output\\\\ConsoleOutput))\\n#18 \\\/var\\\/www\\\/owncloud\\\/lib\\\/private\\\/console\\\/application.php(100): Symfony\\\\Component\\\\Console\\\\Application->run(NULL, NULL)\\n#19 \\\/var\\\/www\\\/owncloud\\\/console.php(79): OC\\\\Console\\\\Application->run()\\n#20 \\\/var\\\/www\\\/owncloud\\\/occ(11): require_once('\\\/var\\\/www\\\/ownclo...')\\n#21 {main}\",\"File\":\"\\\/var\\\/www\\\/owncloud\\\/3rdparty\\\/symfony\\\/routing\\\/Symfony\\\/Component\\\/Routing\\\/Generator\\\/UrlGenerator.php\",\"Line\":134}","level":3,"time":"2016-10-18T17:36:40+00:00","method":"--","url":"--"}
{"reqId":"7CCDiHsGlVmxDvK53Mp9","remoteAddr":"","app":"core","message":"starting upgrade from 8.2.7.1 to 9.0.5.2","level":0,"time":"2016-10-18T17:54:30+00:00","method":"--","url":"--","user":"--"}
{"reqId":"7CCDiHsGlVmxDvK53Mp9","remoteAddr":"","app":"no app in context","message":"Encryption module \"\" not found, file will be stored unencrypted (No default encryption module defined)","level":2,"time":"2016-10-18T17:54:36+00:00","method":"--","url":"--","user":"--"}
{"reqId":"7CCDiHsGlVmxDvK53Mp9","remoteAddr":"","app":"core","message":"No update found at the ownCloud appstore for app 166054","level":0,"time":"2016-10-18T17:54:39+00:00","method":"--","url":"--","user":"--"}
{"reqId":"glMvIeubRfyWLidxs5LF","remoteAddr":"","app":"core","message":"starting upgrade from 9.0.5.2 to 9.1.1.3","level":0,"time":"2016-10-18T18:04:44+00:00","method":"--","url":"--","user":"--"}

Moving to the Miscellaneous category as this is a configuration issue and no oC issue.

To solve your issue you need to fix your webserver setup so it is executing PHP files. Further info like the following should be available with a search on the net:

http://stackoverflow.com/questions/5121495/php-code-is-not-being-executed-instead-code-shows-on-the-page

Thanks, reinstalling php solved it for me