When I try to update from one existing theme to another, I get the error message "Survey could not be updated, please fix the following error: The format of Datecreated is invalid.". See the attached image for the error message in the view. The themes I am switching between are pre-installed themes like "Fruity" and "Vanilla". The exception is raised after clicking the Save button.

I've tried updating a few times from 5.1.17+211025 to 5.2.1+211111 to 5.2.2+211115 and the bug is still present. I also tried resetting all the themes and received the same message.

Current LS version 5.2.2+211115
Database: Postgresql/EnterpriseDB 10.9.17 
 

I enabled logging and found that the following error is being logged:

[error] [application.LimeExpressionManager] setVariableAndTokenMappingsForExpressionManager with an empty surveyOptions.

I see the logging issue about the invalid expression manager started : it's a must fix but this is not the issue here.

I think there are a potential issue with PGSQL and 5.X version …
can you update to last 5.X version, test again ?
If it broke : community.limesurvey.org/bug-tracker/

Here is a link to the solution we arrived at
bugs.limesurvey.org/view.php?id=17730#c67984