I do not self-host, I use the LimeSurvey hosted plan. I am trying to restart an older version of my instance (v2.73.1) that was working as of one year ago. I would like to update it to the latest standard. However, when I attempt the "database Upgrade," I get the following error:

An non-recoverable error happened during the update. Error details:
CDbCommand failed to execute the SQL statement: SQLSTATE[22007]: Invalid datetime format: 1292 Incorrect datetime value: '0000-00-00 00:00:00' for column 'expires' at row 32


File updatedb_helper.php, line 2908.
Please fix this error in your database and try again

I'm not sure how it is possible to fix this error if I cannot get the survey to even come up. Do I need to "Delete this survey application" and start over?

If you are trying to update a hosted account, you can contact LimeSurvey GmbH directly - account.limesurvey.org/customer-support .

Thanks. The support page suggested I try here first, but I guess that makes sense that they are in the best position to help. Wish me luck.

By the way, I would not suggest moving to 4.x for production surveys. 3.x is far more stable at the moment.

They updated our system to v3.23.7. The explanation I got was, "It seems to have been some kind of caching problem." Whatever they did, seems to have done the trick.

Thanks.

So the very next day, after I thought this issue was resolved, I tried to open my instance. I got the same "Invalid datetime format" error, so I resubmitted the help request.

After further investigation, I was told by the support rep that the LimeSurvey system was unable to cope with, "an invalid value set for the 'expires' field in your survey table. This value probably originated from a long time ago when restrictions on valid values weren't as restrictive as they are by today...This issue only came up on further updates of the survey table, which happened recently. The updates were for extending the capacity of certain fields in the table, so the welcome text for example can be longer than 64kb."

Enabling the standard debug mode clears the cache, which apparently gave us the false assurance that everything was OK. However, using an alternative pathway for debugging allowed LimeSurvey technical support to find the underlying issue.