A thousand or so of these:
=#=#=# Syncrun started until (0 msec)
|0|Mailbird|INST_SYNC|Up|1479771903||0||4||0|0|1480604011|5840396b5702e|00000013ocwwtcibli30|INST_NONE|
|0|Mailbird/Misc/CefCache|INST_SYNC|Up|1480117015||0||4||0|0|1480120973|5838da8de7cd2|00000047ocwwtcibli30|INST_NONE|
|0|Mailbird/Misc/CefCache/data_1|INST_SYNC|Up|1480121864||11542528||3|Error downloading http: //site.com/owncloud/remote.php/webdav/Mailbird/Misc/CefCache/data_1-chunking-2023758615-2-0 - server replied: Locked ("Mailbird/Misc/CefCache/data_1" is locked)|423|11542528|1480117267|e6f8be247af6ffc1026fe2975b51a29e|00000093ocwwtcibli30|INST_NONE|
|0|Mailbird/Misc/CefCache/data_3|INST_SYNC|Up|1480121864||16785408||3|Error downloading http: //site.com/owncloud/remote.php/webdav/Mailbird/Misc/CefCache/data_3-chunking-2023763127-2-1 - server replied: Locked ("Mailbird/Misc/CefCache/data_3" is locked)|423|16785408|1479955985|c2036af30fa3aaff7273c927b5801b62|00000107ocwwtcibli30|INST_NONE|
14:57:41|2719|Mailbird/Misc/UsageData.xml|INST_REMOVE|Up|1480602609|3b61577a66f76e6fa3aa9b07cdf116ad|156|00007718ocwwtcibli30|4||204|0|0|||INST_NONE|
|0|Mailbird/Store|INST_SYNC|Up|1480603987||0||4||0|0|1480559820|583f8ccd068d6|00000041ocwwtcibli30|INST_NONE|
|0|Mailbird/Store/MessageIndex/_6t.fdt|INST_REMOVE|Up|1479437620|2d44003e71c870bc268eb4e3599e75b0|0|00000994ocwwtcibli30|3|Error downloading http: //site.com/owncloud/remote.php/webdav/Mailbird/Store/MessageIndex/_6t.fdt - server replied: Locked|423|0|0|||INST_NONE|
|0|Mailbird/Store/Store.db|INST_SYNC|Up|1480602905||7929856||3|Error downloading http: //site.com/owncloud/remote.php/webdav/Mailbird/Store/Store.db - server replied: Locked ("Mailbird/Store/Store.db" is locked)|423|7864320|1480559705|98b4864e087a24946ac9440519823da4|00000056ocwwtcibli30|INST_NONE|
And a thousand or so of these:
{"reqId":"819VZSxBKEPf0JDm3sKn","remoteAddr":"1X3.8X.79.19X","app":"webdav","message":"Exception: {\"Message\":\"HTTP\\/1.1 423 \\"Mailbird\\/Misc\\/CefCache\\/data_1\\" is locked\",\"Exception\":\"OCA\\DAV\\Connector\\Sabre\\Exception\\FileLocked\",\"Code\":0,\"Trace\":\"#0 \\/home\\/username\\/public_html\\/owncloud\\/apps\\/dav\\/lib\\/Connector\\/Sabre\\/File.php(490): OCA\\DAV\\Connector\\Sabre\\File->convertToSabreException(Object(OCP\\Lock\\LockedException))\n#1 \\/home\\/username\\/public_html\\/owncloud\\/apps\\/dav\\/lib\\/Connector\\/Sabre\\/File.php(103): OCA\\DAV\\Connector\\Sabre\\File->createFileChunked(Resource id #372)\n#2 \\/home\\/username\\/public_html\\/owncloud\\/apps\\/dav\\/lib\\/Connector\\/Sabre\\/Directory.php(136): OCA\\DAV\\Connector\\Sabre\\File->put(Resource id #372)\n#3 \\/home\\/username\\/public_html\\/owncloud\\/3rdparty\\/sabre\\/dav\\/lib\\/DAV\\/Server.php(1036): OCA\\DAV\\Connector\\Sabre\\Directory->createFile('data_1-chunking...', Resource id #372)\n#4 \\/home\\/username\\/public_html\\/owncloud\\/3rdparty\\/sabre\\/dav\\/lib\\/DAV\\/CorePlugin.php(523): Sabre\\DAV\\Server->createFile('Mailbird\\/Misc\\/C...', Resource id #372, NULL)\n#5 [internal function]: Sabre\\DAV\\CorePlugin->httpPut(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#6 \\/home\\/username\\/public_html\\/owncloud\\/3rdparty\\/sabre\\/event\\/lib\\/EventEmitterTrait.php(105): call_user_func_array(Array, Array)\n#7 \\/home\\/username\\/public_html\\/owncloud\\/3rdparty\\/sabre\\/dav\\/lib\\/DAV\\/Server.php(459): Sabre\\Event\\EventEmitter->emit('method:PUT', Array)\n#8 \\/home\\/username\\/public_html\\/owncloud\\/3rdparty\\/sabre\\/dav\\/lib\\/DAV\\/Server.php(248): Sabre\\DAV\\Server->invokeMethod(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#9 \\/home\\/username\\/public_html\\/owncloud\\/apps\\/dav\\/appinfo\\/v1\\/webdav.php(56): Sabre\\DAV\\Server->exec()\n#10 \\/home\\/username\\/public_html\\/owncloud\\/remote.php(164): require_once('\\/home\\/username\\/publ...')\n#11 {main}\",\"File\":\"\\/home\\/username\\/public_html\\/owncloud\\/apps\\/dav\\/lib\\/Connector\\/Sabre\\/File.php\",\"Line\":546,\"User\":\"Name\"}","level":4,"time":"2016-11-29T23:01:57+00:00","method":"PUT","url":"\/owncloud\/remote.php\/webdav\/Mailbird\/Misc\/CefCache\/data_1-chunking-2023758615-2-0","user":"Name"}
{"reqId":"Y5hrBERLCg3aY1LggjUk","remoteAddr":"173.81.79.199","app":"webdav","message":"Exception: {\"Message\":\"HTTP\\/1.1 423 \\"Mailbird\\/Misc\\/CefCache\\/data_3\\" is locked\",\"Exception\":\"OCA\\DAV\\Connector\\Sabre\\Exception\\FileLocked\",\"Code\":0,\"Trace\":\"#0 \\/home\\/username\\/public_html\\/owncloud\\/apps\\/dav\\/lib\\/Connector\\/Sabre\\/File.php(490): OCA\\DAV\\Connector\\Sabre\\File->convertToSabreException(Object(OCP\\Lock\\LockedException))\n#1 \\/home\\/username\\/public_html\\/owncloud\\/apps\\/dav\\/lib\\/Connector\\/Sabre\\/File.php(103): OCA\\DAV\\Connector\\Sabre\\File->createFileChunked(Resource id #372)\n#2 \\/home\\/username\\/public_html\\/owncloud\\/apps\\/dav\\/lib\\/Connector\\/Sabre\\/Directory.php(136): OCA\\DAV\\Connector\\Sabre\\File->put(Resource id #372)\n#3 \\/home\\/username\\/public_html\\/owncloud\\/3rdparty\\/sabre\\/dav\\/lib\\/DAV\\/Server.php(1036): OCA\\DAV\\Connector\\Sabre\\Directory->createFile('data_3-chunking...', Resource id #372)\n#4 \\/home\\/username\\/public_html\\/owncloud\\/3rdparty\\/sabre\\/dav\\/lib\\/DAV\\/CorePlugin.php(523): Sabre\\DAV\\Server->createFile('Mailbird\\/Misc\\/C...', Resource id #372, NULL)\n#5 [internal function]: Sabre\\DAV\\CorePlugin->httpPut(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#6 \\/home\\/username\\/public_html\\/owncloud\\/3rdparty\\/sabre\\/event\\/lib\\/EventEmitterTrait.php(105): call_user_func_array(Array, Array)\n#7 \\/home\\/username\\/public_html\\/owncloud\\/3rdparty\\/sabre\\/dav\\/lib\\/DAV\\/Server.php(459): Sabre\\Event\\EventEmitter->emit('method:PUT', Array)\n#8 \\/home\\/username\\/public_html\\/owncloud\\/3rdparty\\/sabre\\/dav\\/lib\\/DAV\\/Server.php(248): Sabre\\DAV\\Server->invokeMethod(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#9 \\/home\\/username\\/public_html\\/owncloud\\/apps\\/dav\\/appinfo\\/v1\\/webdav.php(56): Sabre\\DAV\\Server->exec()\n#10 \\/home\\/username\\/public_html\\/owncloud\\/remote.php(164): require_once('\\/home\\/username\\/publ...')\n#11 {main}\",\"File\":\"\\/home\\/username\\/public_html\\/owncloud\\/apps\\/dav\\/lib\\/Connector\\/Sabre\\/File.php\",\"Line\":546,\"User\":\"Name\"}","level":4,"time":"2016-11-29T23:01:57+00:00","method":"PUT","url":"\/owncloud\/remote.php\/webdav\/Mailbird\/Misc\/CefCache\/data_3-chunking-2023763127-2-1","user":"Name"}
{"reqId":"SDxTCzPEC+BOw3NOIGGQ","remoteAddr":"173.81.79.199","app":"webdav","message":"Exception: {\"Message\":\"HTTP\\/1.1 423 \\"Mailbird\\/Store\\/MessageIndex\\/_6t.fdt\\" is locked\",\"Exception\":\"OCA\\DAV\\Connector\\Sabre\\Exception\\FileLocked\",\"Code\":0,\"Trace\":\"#0 \\/home\\/username\\/public_html\\/owncloud\\/3rdparty\\/sabre\\/dav\\/lib\\/DAV\\/Tree.php(179): OCA\\DAV\\Connector\\Sabre\\File->delete()\n#1 \\/home\\/username\\/public_html\\/owncloud\\/3rdparty\\/sabre\\/dav\\/lib\\/DAV\\/CorePlugin.php(285): Sabre\\DAV\\Tree->delete('Mailbird\\/Store\\/...')\n#2 [internal function]: Sabre\\DAV\\CorePlugin->httpDelete(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#3 \\/home\\/username\\/public_html\\/owncloud\\/3rdparty\\/sabre\\/event\\/lib\\/EventEmitterTrait.php(105): call_user_func_array(Array, Array)\n#4 \\/home\\/username\\/public_html\\/owncloud\\/3rdparty\\/sabre\\/dav\\/lib\\/DAV\\/Server.php(459): Sabre\\Event\\EventEmitter->emit('method:DELETE', Array)\n#5 \\/home\\/username\\/public_html\\/owncloud\\/3rdparty\\/sabre\\/dav\\/lib\\/DAV\\/Server.php(248): Sabre\\DAV\\Server->invokeMethod(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#6 \\/home\\/username\\/public_html\\/owncloud\\/apps\\/dav\\/appinfo\\/v1\\/webdav.php(56): Sabre\\DAV\\Server->exec()\n#7 \\/home\\/username\\/public_html\\/owncloud\\/remote.php(164): require_once('\\/home\\/username\\/publ...')\n#8 {main}\",\"File\":\"\\/home\\/username\\/public_html\\/owncloud\\/apps\\/dav\\/lib\\/Connector\\/Sabre\\/File.php\",\"Line\":342,\"User\":\"Name\"}","level":4,"time":"2016-11-30T02:50:55+00:00","method":"DELETE","url":"\/owncloud\/remote.php\/webdav\/Mailbird\/Store\/MessageIndex\/_6t.fdt","user":"Name"}
(Some specific info has been changed.)