Indexhibit Support

After upgrading from 0.7 to 2.1.6, I can preview an exhibit, but get a blank page when I try to edit.
Eg. url ending in "ndxzstudio/?a=exhibits&q=prv&id=35" shows the page, but "ndxzstudio/?a=exhibits&q=edit&id=35" is blank.
Currently testing how to recover old installation in lab, so no live site to show.
Any tips to how to fix or further troubleshoot?

1. Turning on PHP debug in /ndxzstudio/index.php i get this error logged:
2. PHP Fatal error:  Call to undefined function imagecreatefromjpeg() in [dir]/ndxzstudio/lib/media.php on line 938
3. Switching from PHP v5.6 to 7.0, I get some more details, but still the same error:
4. PHP Fatal error:  Uncaught Error: Call to undefined function imagecreatefromjpeg() in [dir]/ndxzstudio/lib/media.php:938
5. Stack trace:
6. #0 [dir]/ndxzstudio/lib/media.php(234): Media->get_input()
7. #1 [dir]/ndxzstudio/lib/filesourceexhibit.php(86): Media->regenerate('4', '4_plakat.jpg')
8. #2 [dir]/ndxzstudio/module/exhibits/index.php(238): FilesourceExhibit->getExhibitImages('4')
9. #3 [dir]/ndxzstudio/lib/router.php(146): Exhibits->page_edit(NULL)
10. #4 /[dir]/ndxzstudio/index.php(71): Router->tunnel('exhibits', 'exhibits', 'edit')
11. #5 {main}
12.   thrown in [dir]/ndxzstudio/lib/media.php on line 938

I'll try to spin up a newer VM with PHP 7.4 and see if that changes things.

Hello, I have the same problem. But only on some pages… Any thoughts? many thanks