Cannot modify header information - headers already sent

[Notaduck]

Steps to reproduce

Expected behaviour

Tell us what should happen

Actual behaviour

Tell us what happens instead

Server configuration

Operating system: Ubuntu 14.04 LTS

Web server: Apache2

Database: Mysql/MariaDB

PHP version: 5.5.9

Nextcloud version: Lates Build

Updated from an older Nextcloud/ownCloud or fresh install: Migrated from owncloud

Where did you install Nextcloud from: Your guys website

Signing status (Nextcloud 9.0 and above):

Login as admin user into your Nextcloud and access 
http://example.com/index.php/settings/integrity/failed 
No errors have been found.

List of activated apps:

Enabled:
  - activity: 2.2.1
  - admin_audit: 1.0.0
  - comments: 0.2
  - dav: 0.1.6
  - encryption: 1.2.0
  - federatedfilesharing: 0.1.0
  - federation: 0.0.4
  - files: 1.4.4
  - files_pdfviewer: 0.8.1
  - files_sharing: 0.9.1
  - files_texteditor: 2.1
  - files_trashbin: 0.8.0
  - files_versions: 1.2.0
  - files_videoplayer: 0.9.8
  - gallery: 14.5.0
  - notifications: 0.2.3
  - provisioning_api: 0.4.1
  - systemtags: 0.2
  - templateeditor: 0.1
  - updatenotification: 0.1.0
Disabled:
  - external
  - files_external
  - firstrunwizard
  - user_external
  - user_ldap

The content of config/config.php:

<?php
$CONFIG = array (
  'instanceid' => 'xxxxxxxxxxx',
  'passwordsalt' => 'xxxxxxxxxxx',
  'secret' => 'xxxxxxxxxxx',
  'trusted_domains' => 
  array (
    0 => 'xxxxxxxxxxx',
    1 => 'xxxxxxxxxxx',
  ),
  'datadirectory' => 'xxxxxxxxxxx',
  'overwrite.cli.url' => 'http://10.0.2.7',
  'dbtype' => 'mysql',
  'version' => '9.0.50.0',
  'dbname' => 'xxxxxxxxxxx',
  'dbhost' => 'xxxxxxxxxxx,
  'dbtableprefix' => 'xxxxxxxxxxx,
  'dbuser' => 'xxxxxxxxxxx',
  'dbpassword' => 'xxxxxxxxxxx',
  'logtimezone' => 'UTC',
  'installed' => true,
  'theme' => '',
  'loglevel' => 2,
  'maintenance' => false,
  'trashbin_retention_obligation' => 'auto',
  'trusted_proxies' => 
  array (
    0 => 'xxxxxxxxxxx,
  ),
  'overwriteprotocol' => 'https',
  'mail_smtpmode' => 'sendmail',
  'mail_from_address' => 'xxxxxxxxxxx',
  'mail_domain' => 'gmail.com',
  'mail_smtpauthtype' => 'LOGIN',
  'mail_smtpauth' => 1,
  'updatechecker' => false,
  'htaccess.RewriteBase' => '/',
);

Are you using encryption: yes

Client configuration

Browser: Vivaldi

Operating system: Manjaro Deeping

Logs

Nextcloud log (data/owncloud.log)

{"reqId":"qNGsmk+USBT67CsLDUWs","remoteAddr":"10.0.1.3","app":"core","message":"starting upgrade from 9.0.2.2 to 9.0.50.0","level":0,"time":"2016-06-15T18:03:49+00:00","method":"GET","url":"\/core\/ajax\/update.php?fallback=true&fallback_id=0&requesttoken=Zy8XCFQQBn0aWzYvEQMYBDJfZVQKWHRAORUlNzADHl8%3D%3AWnoKeDm8KnNmsyiEyh6lbjL0HzmpwTx1ObzUjBez0rM%3D","user":"--"}
{"reqId":"qNGsmk+USBT67CsLDUWs","remoteAddr":"10.0.1.3","app":"PHP","message":"Cannot modify header information - headers already sent by (output started at \/var\/www\/owncloud\/lib\/private\/eventsource.php:75) at \/var\/www\/owncloud\/lib\/private\/user\/session.php#309","level":3,"time":"2016-06-15T18:03:52+00:00","method":"GET","url":"\/core\/ajax\/update.php?fallback=true&fallback_id=0&requesttoken=Zy8XCFQQBn0aWzYvEQMYBDJfZVQKWHRAORUlNzADHl8%3D%3AWnoKeDm8KnNmsyiEyh6lbjL0HzmpwTx1ObzUjBez0rM%3D","user":"--"}
{"reqId":"qNGsmk+USBT67CsLDUWs","remoteAddr":"10.0.1.3","app":"PHP","message":"Cannot modify header information - headers already sent by (output started at \/var\/www\/owncloud\/lib\/private\/eventsource.php:75) at \/var\/www\/owncloud\/lib\/private\/user\/session.php#310","level":3,"time":"2016-06-15T18:03:52+00:00","method":"GET","url":"\/core\/ajax\/update.php?fallback=true&fallback_id=0&requesttoken=Zy8XCFQQBn0aWzYvEQMYBDJfZVQKWHRAORUlNzADHl8%3D%3AWnoKeDm8KnNmsyiEyh6lbjL0HzmpwTx1ObzUjBez0rM%3D","user":"--"}
{"reqId":"qNGsmk+USBT67CsLDUWs","remoteAddr":"10.0.1.3","app":"PHP","message":"Cannot modify header information - headers already sent by (output started at \/var\/www\/owncloud\/lib\/private\/eventsource.php:75) at \/var\/www\/owncloud\/lib\/private\/user\/session.php#311","level":3,"time":"2016-06-15T18:03:52+00:00","method":"GET","url":"\/core\/ajax\/update.php?fallback=true&fallback_id=0&requesttoken=Zy8XCFQQBn0aWzYvEQMYBDJfZVQKWHRAORUlNzADHl8%3D%3AWnoKeDm8KnNmsyiEyh6lbjL0HzmpwTx1ObzUjBez0rM%3D","user":"--"}
{"reqId":"qNGsmk+USBT67CsLDUWs","remoteAddr":"10.0.1.3","app":"PHP","message":"Cannot modify header information - headers already sent by (output started at \/var\/www\/owncloud\/lib\/private\/eventsource.php:75) at \/var\/www\/owncloud\/lib\/private\/user\/session.php#314","level":3,"time":"2016-06-15T18:03:52+00:00","method":"GET","url":"\/core\/ajax\/update.php?fallback=true&fallback_id=0&requesttoken=Zy8XCFQQBn0aWzYvEQMYBDJfZVQKWHRAORUlNzADHl8%3D%3AWnoKeDm8KnNmsyiEyh6lbjL0HzmpwTx1ObzUjBez0rM%3D","user":"--"}
{"reqId":"qNGsmk+USBT67CsLDUWs","remoteAddr":"10.0.1.3","app":"PHP","message":"Cannot modify header information - headers already sent by (output started at \/var\/www\/owncloud\/lib\/private\/eventsource.php:75) at \/var\/www\/owncloud\/lib\/private\/user\/session.php#315","level":3,"time":"2016-06-15T18:03:52+00:00","method":"GET","url":"\/core\/ajax\/update.php?fallback=true&fallback_id=0&requesttoken=Zy8XCFQQBn0aWzYvEQMYBDJfZVQKWHRAORUlNzADHl8%3D%3AWnoKeDm8KnNmsyiEyh6lbjL0HzmpwTx1ObzUjBez0rM%3D","user":"--"}
{"reqId":"qNGsmk+USBT67CsLDUWs","remoteAddr":"10.0.1.3","app":"PHP","message":"Cannot modify header information - headers already sent by (output started at \/var\/www\/owncloud\/lib\/private\/eventsource.php:75) at \/var\/www\/owncloud\/lib\/private\/user\/session.php#316","level":3,"time":"2016-06-15T18:03:52+00:00","method":"GET","url":"\/core\/ajax\/update.php?fallback=true&fallback_id=0&requesttoken=Zy8XCFQQBn0aWzYvEQMYBDJfZVQKWHRAORUlNzADHl8%3D%3AWnoKeDm8KnNmsyiEyh6lbjL0HzmpwTx1ObzUjBez0rM%3D","user":"--"}
{"reqId":"pqIYvYMXamyyVtodDUTS","remoteAddr":"10.0.1.3","app":"files","message":"Can't write upload limit to \/var\/www\/owncloud\/.htaccess. Please check the file permissions","level":2,"time":"2016-06-15T18:28:22+00:00","method":"POST","url":"\/index.php\/settings\/admin","user":"notaduck"}
root@Owncloud:/media/sdb/data# 

[MorrisJobke]

@Notaduck Could you provide more information? This could mean anything. Did the upgrade succeed after the messages appeared? Where there any error messages in the browser visible? Otherwise there is not much we could do here beside guessing what happened :(

[MorrisJobke]

No response for 3 months -> closing