8.2 Files Not Found Exception

Running owncloud on a redhat 6.6 machine. This server has been working fine for some weeks. It had an odd glitch where the ldap password needed to be reset, but then worked again fine. As of this week, with no known changes to the system, an owncloud web connection immediately gives the message "Internal Service Error" (see log including NotFoundException below). All commands seem fine using the command line interface occ as user "apache", the user associated with the web server. For instance, occ ldap:test-config shows "The configuration is valid and the connection could be established". Similarly, occ files:scan USER proceeds with no errors.

Server configuration
Operating system: Redhat 6.6
Web server: Apache 2.4.12-3
Database: MariaDB 5.5.41-12
PHP version: 5.6.5
ownCloud version (see ownCloud admin page): 8.2.7.1.1
Updated from an older ownCloud or fresh install: Updated
ownCloud log):

{"reqId":"V@rYzLJkvxxvah2e3auwcQAAAAc","remoteAddr":"128.138.140.30","app":"index","message":"Exception: {\"Exception\":\"OCP\\\\Files\\\\NotFoundException\",\"Message\":\"\",\"Code\":0,\"Trace \":\"
#0 /var/www/html/owncloud/apps/files/index.php(92): OC_Helper::getStorageInfo('\\\/', false)
#1 /var/www/html/owncloud/lib/private/route/route.php(154) : runtime-created function(1): require_once('\\\/var\\\/www\\\/html\\\/o...')
#2 [internal function]: __lambda_func(Array)
#3 /var/www/html/owncloud/lib/private/route/router.php(291): call_user_func('\\\\x00lambda_58', Array)
#4 /var/www/html/owncloud/lib/base.php(853): OC\\\\Route\\\\Router->match('\\\/apps\\\/files\\\/')
#5 /var/www/html/owncloud/index.php(39): OC::handleRequest()
#6 {main}\",\"File\":\"/var/www/html/owncloud/lib/private/helper.php\",\"Line\":841}","level": 3,"time":"2016-09-27T14:38:37-06:00"}

{"reqId":"V@rYzf0pEGeiBEw4DoaYuwAAAAM","remoteAddr":"128.138.140.30","app":"index","message":"Exception: {\"Exception\":\"OCP\\\\Files\\\\NotFoundException\",\"Message\":\"\",\"Code\":0,\"Trace\":\"
#0 /var/www/html/owncloud/lib/private/files/node/node.php(221): OC\\\\Files\\\\Node\\\\Node->getFileInfo()
#1 /var/www/html/owncloud/lib/private/files/node/node.php(104): OC\\\\Files\\\\Node\\\\Node->getPermissions()
#2 /var/www/html/owncloud/lib/private/files/node/folder.php(139): OC\\\\Files\\\\Node\\\\Node->checkPermissions(4)
#3 /var/www/html/owncloud/lib/private/files/node/root.php(346): OC\\\\Files\\\\Node\\\\Folder->newFolder('\\\/files')
#4 /var/www/html/owncloud/lib/private/server.php(620): OC\\\\Files\\\\Node\\\\Root->getUserFolder('nefr2840')
#5 /var/www/html/owncloud/apps/gallery/appinfo/application.php(234): OC\\\\Server->getUserFolder('nefr2840')
#6 /var/www/html/owncloud/3rdparty/pimple/pimple/src/Pimple/Container.php(112): OCA\\\\Gallery\\\\AppInfo\\\\Application->OCA\\\\Gallery\\\\AppInfo\\\\{closure}(Object(OC\\\\AppFramework\\\\DependencyInjection\\\\DIContainer))
#7 /var/www/html/owncloud/lib/private/appframework/utility/simplecontainer.php(104): Pimple\\\\Container->offsetGet('UserFolder')
#8 /var/www/html/owncloud\apps/gallery/appinfo/application.php(260): OC\\\\AppFramework\\\\Utility\\\\SimpleContainer->query('UserFolder')
#9 /var/www/html/owncloud/3rdparty/pimple/pimple/src/Pimple/Container.php(112): OCA\\\\Gallery\\\\AppInfo\\\\Application->OCA\\\\Gallery\\\\AppInfo\\\\{closure}(Object(OC\\\\AppFramework\\\\DependencyInjection\\\\DIContainer))
#10 /var/www/html/owncloud/lib/private/appframework/utility/simplecontainer.php(104): Pimple\\\\Container->offsetGet('Environment')
#11 /var/www/html/owncloud/apps/gallery/appinfo/application.php(327): OC\\\\AppFramework\\\\Utility\\\\SimpleContainer->query('Environment')
#12 /var/www/html/owncloud/3rdparty/pimple/pimple/src/Pimple/Container.php(112): OCA\\\\Gallery\\\\AppInfo\\\\Application->OCA\\\\Gallery\\\\AppInfo\\\\{closure}(Object(OC\\\\AppFramework\\\\DependencyInjection\\\\DIContainer))
#13 /var/www/html/owncloud/lib/private/appframework/utility/simplecontainer.php(104): Pimple\\\\Container->offsetGet('ConfigService')
#14 /var/www/html/owncloud/apps/gallery/appinfo/application.php(92): OC\\\\AppFramework\\\\Utility\\\\SimpleContainer->query('ConfigService')
#15 /var/www/html/owncloud/3rdparty/pimple/pimple/src/Pimple/Container.php(112): OCA\\\\Gallery\\\\AppInfo\\\\Application->OCA\\\\Gallery\\\\AppInfo\\\\{closure}(Object(OC\\\\AppFramework\\\\DependencyInjection\\\\DIContainer))
#16 /var/www/html/owncloud/lib/private/appframework/utility/simplecontainer.php(104): Pimple\\\\Container->offsetGet('ConfigControlle...')
#17 /var/www/html/owncloud/lib/private/appframework/app.php(92): OC\\\\AppFramework\\\\Utility\\\\SimpleContainer->query('ConfigControlle...')
#18 /var/www/html/owncloud/lib/private/appframework/routing/routeactionhandler.php(45): OC\\\\AppFramework\\\\App::main('ConfigControlle...', 'get', Object(OC\\\\AppFramework\\\\DependencyInjection\\\\DIContainer), Array)
#19 [internal function]: OC\\\\AppFramework\\\\routing\\\\RouteActionHandler->__invoke(Array)
#20 /var/www/html/owncloud/lib/private/route/router.php(291): call_user_func(Object(OC\\\\AppFramework\\\\routing\\\\RouteActionHandler), Array)
#21 /var/www/html/owncloud/lib/base.php(853): OC\\\\Route\\\\Router->match('\\\/apps\\\/gallery\\\/c...')
#22 /var/www/html/owncloud/index.php(39): OC::handleRequest()
#23 {main}\",\"File\":\"/var/www/html/owncloud/lib/private/files/node/node.php\",\"Line\":84}","level":3,"

Special configuration (external storage, external authentication, reverse proxy, server-side-encryption):
none

Integrity status for oC9+
No status available since all web access results in internal error.

Sorry to bother people here, but this might be of use to others. I cleared the browser and the problem seems to have vanished. Why is it always the last place you look?