Cant login to server.

Enabled:
  - accessibility: 1.0.1
  - activity: 2.7.0
  - admin_audit: 1.4.0
  - cloud_federation_api: 0.0.1
  - comments: 1.4.0
  - dav: 1.6.0
  - federatedfilesharing: 1.4.0
  - federation: 1.4.0
  - files: 1.9.0
  - files_external: 1.5.0
  - files_pdfviewer: 1.3.2
  - files_sharing: 1.6.2
  - files_texteditor: 2.6.0
  - files_trashbin: 1.4.1
  - files_versions: 1.7.1
  - files_videoplayer: 1.3.0
  - firstrunwizard: 2.3.0
  - gallery: 18.1.0
  - logreader: 2.0.0
  - lookup_server_connector: 1.2.0
  - nextcloud_announcements: 1.3.0
  - notifications: 2.2.1
  - oauth2: 1.2.1
  - password_policy: 1.4.0
  - provisioning_api: 1.4.0
  - serverinfo: 1.4.0
  - sharebymail: 1.4.0
  - support: 1.0.0
  - survey_client: 1.2.0
  - systemtags: 1.4.0
  - theming: 1.5.0
  - twofactor_backupcodes: 1.3.1
  - updatenotification: 1.4.1
  - workflowengine: 1.4.0
Disabled:
  - encryption
  - user_external
  - user_ldap

{
    "system": {
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "forcessl": true,
        "asset-pipeline.enabled": true,
        "maxZipInputSize": 0,
        "allowZipDownload": true,
        "trusted_domains": [
            "xxx",
            "xxx",
            "xxx",
            "xxx"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "overwrite.cli.url": "https:\/\/xxx.de",
        "dbtype": "mysql",
        "version": "14.0.0.19",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbtableprefix": "oc_",
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "logtimezone": "Europe\/Berlin",
        "installed": true,
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpmode": "php",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "logdateformat": "F d, Y H:i:s",
        "log_rotate_size": 104857600,
        "logfile": "\/var\/log\/nextcloud\/nextcloud.log",
        "loglevel": 1,
        "theme": "",
        "maintenance": false,
        "memcache.local": "\\OC\\Memcache\\APCu",
        "appstore.experimental.enabled": true,
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "ldapIgnoreNamingRules": false,
        "ldapProviderFactory": "\\OCA\\User_LDAP\\LDAPProviderFactory",
        "mail_smtpauthtype": "LOGIN",
        "mail_smtpsecure": "tls",
        "mail_smtpauth": 1,
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "587",
        "data-fingerprint": "xxx",
        "openssl": {
            "config": "\/etc\/ssl\/openssl.cnf"
        }
    }
}

nothing relevant in apache2 error log.

{"reqId":"W5wPsAUJdq4AAGE@@nkAAAAG","level":3,"time":"September 14, 2018 21:44:48","remoteAddr":"xxx","user":"Marcwa19197","app":"PHP","method":"POST","url":"\/index.php\/login","message":"openssl_pkey_export(): cannot get key from parameter 1 at \/data\/www\/xxx.de\/public_data\/lib\/private\/Authentication\/Token\/PublicKeyTokenProvider.php#297","userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit\/537.36 (KHTML, like Gecko) Chrome\/69.0.3497.92 Safari\/537.36","version":"14.0.0.19"}
{"reqId":"W5wPsAUJdq4AAGE@@nkAAAAG","level":3,"time":"September 14, 2018 21:44:48","remoteAddr":"87.149.175.121","user":"Marcwa19197","app":"index","method":"POST","url":"\/index.php\/login","message":{"Exception":"TypeError","Message":"openssl_pkey_get_details() expects parameter 1 to be resource, boolean given","Code":0,"Trace":[{"file":"\/data\/www\/xxx.de\/public_data\/lib\/private\/Authentication\/Token\/PublicKeyTokenProvider.php","line":300,"function":"openssl_pkey_get_details","args":[false]},{"file":"\/data\/www\/xxx.de\/public_data\/lib\/private\/Authentication\/Token\/PublicKeyTokenProvider.php","line":69,"function":"newToken","class":"OC\\Authentication\\Token\\PublicKeyTokenProvider","type":"->","args":["*** sensitive parameter replaced ***","*** sensitive parameter replaced ***","*** sensitive parameter replaced ***","*** sensitive parameter replaced ***","*** sensitive parameter replaced ***","*** sensitive parameter replaced ***","*** sensitive parameter replaced ***"]},{"file":"\/data\/www\/xxx.de\/public_data\/lib\/private\/Authentication\/Token\/Manager.php","line":68,"function":"generateToken","class":"OC\\Authentication\\Token\\PublicKeyTokenProvider","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"\/data\/www\/xxx.de\/public_data\/lib\/private\/User\/Session.php","line":631,"function":"generateToken","class":"OC\\Authentication\\Token\\Manager","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"\/data\/www\/xxx.de\/public_data\/core\/Controller\/LoginController.php","line":322,"function":"createSessionToken","class":"OC\\User\\Session","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"\/data\/www\/xxx.de\/public_data\/lib\/private\/AppFramework\/Http\/Dispatcher.php","line":166,"function":"tryLogin","class":"OC\\Core\\Controller\\LoginController","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"\/data\/www\/xxx.de\/public_data\/lib\/private\/AppFramework\/Http\/Dispatcher.php","line":99,"function":"executeController","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->","args":[{"__class__":"OC\\Core\\Controller\\LoginController"},"tryLogin"]},{"file":"\/data\/www\/xxx.de\/public_data\/lib\/private\/AppFramework\/App.php","line":118,"function":"dispatch","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->","args":[{"__class__":"OC\\Core\\Controller\\LoginController"},"tryLogin"]},{"file":"\/data\/www\/xxx.de\/public_data\/lib\/private\/AppFramework\/Routing\/RouteActionHandler.php","line":47,"function":"main","class":"OC\\AppFramework\\App","type":"::","args":["OC\\Core\\Controller\\LoginController","tryLogin",{"__class__":"OC\\AppFramework\\DependencyInjection\\DIContainer"},{"_route":"core.login.tryLogin"}]},{"function":"__invoke","class":"OC\\AppFramework\\Routing\\RouteActionHandler","type":"->","args":[{"_route":"core.login.tryLogin"}]},{"file":"\/data\/www\/xxx.de\/public_data\/lib\/private\/Route\/Router.php","line":297,"function":"call_user_func","args":[{"__class__":"OC\\AppFramework\\Routing\\RouteActionHandler"},{"_route":"core.login.tryLogin"}]},{"file":"\/data\/www\/xxx.de\/public_data\/lib\/base.php","line":989,"function":"match","class":"OC\\Route\\Router","type":"->","args":["\/login"]},{"file":"\/data\/www\/xxx.de\/public_data\/index.php","line":42,"function":"handleRequest","class":"OC","type":"::","args":[]}],"File":"\/data\/www\/xxx.de\/public_data\/lib\/private\/Authentication\/Token\/PublicKeyTokenProvider.php","Line":300,"CustomMessage":"--"},"userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit\/537.36 (KHTML, like Gecko) Chrome\/69.0.3497.92 Safari\/537.36","version":"14.0.0.19"}

not relevant.