PDOException: SQLSTATE[HY000]: General error: 1 cannot commit transaction - SQL statements in progress

Hello,
im amateur owncloud user and trying update owncloud on qnap server from 8.2.2 to 8.2.9.
When im connecting from web and trying update, i see this text. What I need to do?:

Updating ownCloud to version 8.2.9, this may take a while.

Preparing update
Set log level to debug - current level: "Warning"
Turned on maintenance mode
Checking whether the database schema can be updated (this can take a long time depending on the database size)
Checked database schema update
Checking updates of apps
Checked database schema update for apps
Updating database schema
Updated database
PDOException: SQLSTATE[HY000]: General error: 1 cannot commit transaction - SQL statements in progress