When you are updating your Joomla! website to the Joomla! 3.7.1 version using the built in Joomla! Update extension, the following or similar error message could appear
How to fix Joomla 3.7.1 Update Issue
- When you return to Control Panel you can see Unknown Joomla.. Under MAINTENANCE
- Go to Extensions->Manage->Database
- You can see list of Database Problems Found.
- Click on Fix button and wait until fixing script stop running.
- Now appear new Notice : Database table structure is up to date.
- Return to Control Panel to make sure that Joomla! is up to date now.