Please help us help you and fill where relevant:
Your LimeSurvey version: Version 6.2.0+230732
Own server or LimeSurvey hosting: Own server
Survey theme/template: Extended Vanilla
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Hi, after recently updating to v6.2.0 from 6.1.8 we have issues with our theme. If we preview a pre-existing survey that uses the theme, the console in the browser will read "themescripts not defined" and "tooltip is not a function" on page load. If we attempt to import the theme from a backup it responds that the theme was uninstalled since it is incompatible. Any ideas? Thank you for any help! 

Looking forward: If this is ultimately considered a bug, please post the bug on our behalf since we continue to not be able to login to post our own bugs due to an ongoing issue with that application. Thanks! 
 

Reported - bugs.limesurvey.org/view.php?id=19006

Same for us, nice shock to see 50+ active surveys being reset   Thanks for reporting the bug already @tpartner!

Tony, I see the conversation in the bug tracker and the most current response reads

"Thanks  @tibor.pacalat  – the issue is user experience. In my case: the theme got disabled silently, no warning in the backend issued, all active surveys fell back to the new fruity2023 theme, which does not yet cover several of the question types we are using, all custom.css is gone, all survey settings are changed back to standards. It caused a moment of panic, followed by hours of work." 

I'm not sure if the following detail is needed, but in case it helps:

In addition to the issue noted above whereby a theme had lost its association with a previously assigned custom theme and it did this without warning (UX issue), there is a secondary issue. When we attempt to import a theme into v6.2.0 that we had previously exported from 6.1.8, we receive an error (noted in my original post at the top of the thread). 

I wanted to clarify this in case all of the attention is just on the one half of the problem related to themes and the upgrade. This other issue is also substantial and doesn't appear to be a UX challenge but inhibits the ability to import the theme when prior to v6.2.0 it was not a challenge. 

Thanks.to both of you (Tony and NonFormality)

Please add these extra details to the bug report.

I'll see if it allows me to login yet - or post anonymously, otherwise I won't be able to post them. Let me give it a try... thanks

For anyone reading along and wondering whether there is a work around – **before updating**, you should add a compatibility statement to the config.xml of your actively used themes, right after the metadata section, like so:

With that, your theme should be fine until the next major version jump to LimeSurvey 7.

Note that you cannot do this from within LimeSurvey – the Theme Editor does not give you access to the config.xml file of your theme. You'll need to do this directly on your server.

See the manual for more details: manual.limesurvey.org/Extension_compatibility

Thanks, but some outstanding issues/questions...

That will not help people using the hosted version where they only have access to th GUI to extend themes.

Why doesn't the GUI insert that compatability tag when creating the extended theme?

Why did this problem only occur with updates to 6.2.x, not any previous 6.x updates.

Why was there no notice about trashing the existing themes?

Agree with you an all of these open questions! Just wanted to drop the info in case it helps someone.