Support intro
Sorry to hear you’re facing problems 
help.nextcloud.com is for home/non-enterprise users. If you’re running a business, paid support can be accessed via portal.nextcloud.com where we can ensure your business keeps running smoothly.
In order to help you as quickly as possible, before clicking Create Topic please provide as much of the below as you can. Feel free to use a pastebin service for logs, otherwise either indent short log examples with four spaces:
example
Or for longer, use three backticks above and below the code snippet:
longer
example
here
Some or all of the below information will be requested if it isn’t supplied; for fastest response please provide as much as you can 
Nextcloud version : 16.0.2
Operating system and version : Linux ovt5-web07 4.19.0
Apache or nginx version : Apache/2.4.25 (Debian)
PHP version : 7.1.28
The issue you are facing:
last thursday, I started auto update from 15.0.6 to 16.0.2. After many trials and failures (mostly blocking at step 6), I finished by a manual update (with fear!).
Friday noon, the system was up, web access was OK and CalDAV too. However, connexion to the instance by the desktop (MacOS) app and the mobile (iOS) app is impossible.
It’s not a problem of credentials, id and password are ok.
Here is a screenshot with the error message in Mac Desktop App.
I tried a direct connexion with the MacOs finder, same problem.
When I check the log in Parameters / Admin / Logging, I don’t find any errors related to the failed connexion. I’m not at ease with this journaling system, I don’t know how to reduce the amount for messages (removing info for example).
Is this the first time you’ve seen this error? : Y!
The output of your Nextcloud log in Admin > Logging:
(too many messages, how can I find the interesting ones?)
The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):
<?php
$CONFIG = array (
'instanceid' => 'ocm6gs5eujtq',
'passwordsalt' => 'hidden',
'secret' => 'hidden',
'trusted_domains' =>
array (
0 => 'nuage.pambio.fr',
),
'datadirectory' => '/var/www/vhosts/nuage.pambio.fr/httpdocs/data',
'overwrite.cli.url' => 'http://nuage.pambio.fr',
'dbtype' => 'mysql',
'version' => '16.0.2.1',
'dbname' => '08159_pambio',
'dbhost' => 'hidden.server',
'dbport' => '',
'dbtableprefix' => 'oc_',
'dbuser' => '08159_pambio',
'dbpassword' => 'hidden',
'installed' => true,
'mail_domain' => 'pambio.fr',
'mail_from_address' => 'bienvenue',
'mail_smtpmode' => 'smtp',
'maintenance' => false,
'theme' => '',
'loglevel' => 2,
'mail_sendmailmode' => 'smtp',
'mail_smtphost' => 'smtp.ouvaton.coop',
'mail_smtpport' => '587',
'mail_smtpauthtype' => 'LOGIN',
'mail_smtpauth' => 1,
'mail_smtpname' => 'hidden',
'mail_smtppassword' => 'hidden',
'mail_smtpsecure' => 'tls',
'updater.secret' => 'hidden',
'app_install_overwrite' =>
array (
0 => 'calendar',
),
);
The output of your Apache/nginx/system log in /var/log/____:
(I don't have access to that)
Many thanks for any help!
Stéphane.