some slideshow with error 500

Hi,
I have many sites with slideshows.
I setup the first slideshow and then I saved the modul as a copy with the new images.
I use the free version and I selected all the images from the media manager.
But many of the sites crashes in the frontend.
What causes the problem? And how can I solve it?
The error report shows me that:Attempted to call function "imagecreatefromjpeg" from the global namespace. Symfony\Component\ErrorHandler\Error\ UndefinedFunctionErrorin xxxx\administrator\components\com_slideshowck\helpers\helper.php (line 236)  
 

If I deactivate "Create the thumbnails automatically" everything is fine.

Hi
thank you for your feedback. YEs this is related to the thumbs creation

I will try to recreate the problem by my side to fix i
CEd

Thank you very much