Internal server error webdav

Hello,
Since today i got the following message on my nextcloud homepage:

internal Server Error

The server encountered an internal error and was unable to complete your request.
Please contact the server administrator if this error reappears multiple times, please include the technical details below in your report.
More details can be found in the server log

Here is my Nextcloud.log with level 4 error
What could be the cause of my problem?
{"reqId":"2LSG13vo1x6ifbUAQ1g4","level":4,"time":"2018-05-05T16:26:19+00:00","remoteAddr":"192.168.142.128","user":"wouter","app":"webdav","method":"GET","url":"\/remote.php\/dav\/files\/wouter\/fiets\/Foto's%20fietsen\/Peugeot%20aubisque\/IMG_20160404_193019.jpg","message":"Exception: {\"Exception\":\"Doctrine\\\\DBAL\\\\Exception\\\\UniqueConstraintViolationException\",\"Message\":\"An exception occurred while executing 'INSERT INTOoc_file_locks(key,lock,ttl) SELECT ?,?,? FROMoc_file_locksWHEREkey= ? HAVING COUNT(*) = 0' with params [\\\"files\\\\\\\/45548ebcc47a37ed9831dbaaa0028ee8\\\", 1, 1525541179, \\\"files\\\\\\\/45548ebcc47a37ed9831dbaaa0028ee8\\\"]:\\n\\nSQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry 'files\\\/45548ebcc47a37ed9831dbaaa0028ee8' for key 'lock_key_index'\",\"Code\":0,\"Trace\":\"#0 \\\/var\\\/www\\\/nextcloud\\\/3rdparty\\\/doctrine\\\/dbal\\\/lib\\\/Doctrine\\\/DBAL\\\/DBALException.php(128): Doctrine\\\\DBAL\\\\Driver\\\\AbstractMySQLDriver->convertException('An exception oc...', Object(Doctrine\\\\DBAL\\\\Driver\\\\PDOException))\\n#1 \\\/var\\\/www\\\/nextcloud\\\/3rdparty\\\/doctrine\\\/dbal\\\/lib\\\/Doctrine\\\/DBAL\\\/Connection.php(1015): Doctrine\\\\DBAL\\\\DBALException::driverExceptionDuringQuery(Object(Doctrine\\\\DBAL\\\\Driver\\\\PDOMySql\\\\Driver), Object(Doctrine\\\\DBAL\\\\Driver\\\\PDOException), 'INSERT INTOoc…’, Array)\n#2 \/var\/www\/nextcloud\/lib\/private\/DB\/Connection.php(216): Doctrine\\DBAL\\Connection->executeUpdate(‘INSERT INTO oc...', Array, Array)\\n#3 \\\/var\\\/www\\\/nextcloud\\\/lib\\\/private\\\/DB\\\/Adapter.php(114): OC\\\\DB\\\\Connection->executeUpdate('INSERT INTO*P…’, Array)\n#4 \/var\/www\/nextcloud\/lib\/private\/DB\/Connection.php(254): OC\\DB\\Adapter->insertIfNotExist(‘PREFIXfile_lo…’, Array, Array)\n#5 \/var\/www\/nextcloud\/lib\/private\/Lock\/DBLockingProvider.php(119): OC\\DB\\Connection->insertIfNotExist(‘PREFIXfile_lo…’, Array, Array)\n#6 \/var\/www\/nextcloud\/lib\/private\/Lock\/DBLockingProvider.php(164): OC\\Lock\\DBLockingProvider->initLockField(‘files\/45548ebcc…’, 1)\n#7 \/var\/www\/nextcloud\/lib\/private\/Files\/Storage\/Common.php(709): OC\\Lock\\DBLockingProvider->acquireLock(‘files\/45548ebcc…’, 1)\n#8 \/var\/www\/nextcloud\/lib\/private\/Files\/Storage\/Wrapper\/Wrapper.php(592): OC\\Files\\Storage\\Common->acquireLock(‘files\/fiets\/Fot…’, 1, Object(OC\\Lock\\DBLockingProvider))\n#9 \/var\/www\/nextcloud\/lib\/private\/Files\/Storage\/Wrapper\/Wrapper.php(592): OC\\Files\\Storage\\Wrapper\\Wrapper->acquireLock(‘files\/fiets\/Fot…’, 1, Object(OC\\Lock\\DBLockingProvider))\n#10 \/var\/www\/nextcloud\/lib\/private\/Files\/View.php(1927): OC\\Files\\Storage\\Wrapper\\Wrapper->acquireLock(‘files\/fiets\/Fot…’, 1, Object(OC\\Lock\\DBLockingProvider))\n#11 \/var\/www\/nextcloud\/lib\/private\/Files\/View.php(2040): OC\\Files\\View->lockPath(’\/fiets\/Foto’s f…’, 1)\n#12 \/var\/www\/nextcloud\/lib\/private\/Files\/View.php(1134): OC\\Files\\View->lockFile(’\/fiets\/Foto’s f…’, 1)\n#13 \/var\/www\/nextcloud\/lib\/private\/Files\/View.php(987): OC\\Files\\View->basicOperation(‘fopen’, ‘fiets\/Foto’s fi…’, Array, ‘r’)\n#14 \/var\/www\/nextcloud\/apps\/dav\/lib\/Connector\/Sabre\/File.php(335): OC\\Files\\View->fopen(‘fiets\/Foto’s fi…’, ‘rb’)\n#15 \/var\/www\/nextcloud\/3rdparty\/sabre\/dav\/lib\/DAV\/CorePlugin.php(85): OCA\\DAV\\Connector\\Sabre\\File->get()\n#16 [internal function]: Sabre\\DAV\\CorePlugin->httpGet(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#17 \/var\/www\/nextcloud\/3rdparty\/sabre\/event\/lib\/EventEmitterTrait.php(105): call_user_func_array(Array, Array)\n#18 \/var\/www\/nextcloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Server.php(479): Sabre\\Event\\EventEmitter->emit(‘method:GET’, Array)\n#19 \/var\/www\/nextcloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Server.php(254): Sabre\\DAV\\Server->invokeMethod(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#20 \/var\/www\/nextcloud\/apps\/dav\/lib\/Server.php(283): Sabre\\DAV\\Server->exec()\n#21 \/var\/www\/nextcloud\/apps\/dav\/appinfo\/v2\/remote.php(35): OCA\\DAV\\Server->exec()\n#22 \/var\/www\/nextcloud\/remote.php(164): require_once(’\/var\/www\/nextcl…’)\n#23 {main}",“File”:"\/var\/www\/nextcloud\/3rdparty\/doctrine\/dbal\/lib\/Doctrine\/DBAL\/Driver\/AbstractMySQLDriver.php",“Line”:66}",“userAgent”:“Mozilla/5.0 (Linux) mirall/2.3.3 (build 1) (Nextcloud)”,“version”:“13.0.2.1”}`

Nevermind… Turned out one of my hard drives was powered off hence nextcloud could not find the filed.