Support intro
Sorry to hear you’re facing problems 
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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 (eg, 20.0.5): 24.0.12.1 → 26.0.3.2
Operating system and version (eg, Ubuntu 20.04): Docker Apache Image
Apache or nginx version (eg, Apache 2.4.25): Docker Apache Image
PHP version (eg, 7.4): Docker Apache Image
The issue you are facing:
I updated to 26 using the stable tag but I got the error Exception: Updates between multiple major versions and downgrades are unsupported.
I then tried to go back to version 24 but I’m getting the error Can't start Nextcloud because the version of the data (26.0.3.2) is higher than the docker image version (24.0.12.1) and downgrading is not supported. Are you sure you have pulled the newest image version?
Is it possible for me to change the version of my database back to 24? I’m not sure 26 even updated anything.
Is this the first time you’ve seen this error? (Y/N): Y
Steps to replicate it:
- Be on version 24
- Try to update to version 26
- Notice update will not be possible
- Notice downgraded doesn’t work either
<?php
$CONFIG = array (
'datadirectory' => '/var/www/html/data',
'memcache.local' => '\\OC\\Memcache\\APCu',
'instanceid' => 'xxxxxx',
'passwordsalt' => 'xxxx',
'secret' => 'xxxxx',
'overwriteprotocol' => 'https',
'trusted_domains' =>
array (
0 => 'xxxxxt',
),
'trusted_proxies' =>
array (
0 => 'xxxxxx',
),
'apps_paths' =>
array (
0 =>
array (
'path' => '/var/www/html/apps',
'url' => '/apps',
'writable' => false,
),
1 =>
array (
'path' => '/var/www/html/custom_apps',
'url' => '/custom_apps',
'writable' => true,
),
),
'overwrite.cli.url' => 'https://xxxxx.xxxx',
'check_for_working_wellknown_setup' => false,
'dbtype' => 'mysql',
'version' => '24.0.12.1',
'dbname' => 'nextcloud',
'dbhost' => 'db',
'dbport' => '',
'dbtableprefix' => 'oc_',
'mysql.utf8mb4' => true,
'dbuser' => 'nextcloud',
'dbpassword' => 'xxxx',
'installed' => true,
'mail_from_address' => 'postmaster',
'logtimezone' => 'Etc/UTC',
'logdateformat' => 'Y-m-d H:i:s',
...
'default_phone_region' => 'US',
'loglevel' => 0,
'maintenance' => true,
'theme' => '',
'updater.release.channel' => 'stable',
'app_install_overwrite' =>
array (
0 => 'spreed',
1 => 'twofactor_totp',
),
);