Nextcloud update to 20.0.7 fails

[wfinke]

Doctrine\DBAL\Exception\DriverException: An exception occurred while executing 'CREATE UNIQUE INDEX UNIQ_options ON oc_polls_options (poll_id, poll_option_text, timestamp)': SQLSTATE[42000]: Syntax error or access violation: 1071 Specified key was too long; max key length is 767 bytes
Detailed logs

Preparing update

Set log level to debug

Turned on maintenance mode

Repair step: Repair MySQL collation

Repair info: All tables already have the correct collation -> nothing to do

Repair step: Repair SQLite autoincrement

Repair step: Copy data from accounts table when migrating from ownCloud

Repair step: Drop account terms table when migrating from ownCloud

Updating database schema

Updated database

Repair step: Delete duplicates

Doctrine\DBAL\Exception\DriverException: An exception occurred while executing 'CREATE UNIQUE INDEX UNIQ_options ON oc_polls_options (poll_id, poll_option_text, timestamp)': SQLSTATE[42000]: Syntax error or access violation: 1071 Specified key was too long; max key length is 767 bytes

[kesselb]

Thank you for reporting this issue 👍 Please check #15058 for more details.

Usually there are two ways to fix this:

A) Configure your database server to support utf8mb4 (https://docs.nextcloud.com/server/latest/admin_manual/configuration_database/mysql_4byte_support.html).

B) If the database server does not support utf8mb4 disable it by setting 'mysql.utf8mb4' => false in your config.php (emojis in filename, calendar events, etc. are not possible than and you have to accept the warning).