Thumbs are not generated img2thumb newimgcreate imagecreatefromstring failed

[welrachid]

Hi
Im having a problem with a shop that cannot generate thumbs. Only thing i did a few weeks ago was updating to J! 3.6.1 and last week i updated to 3.6.2

VM version is 3.0.16

I've tried with PHP versions:
5.4.45
5.6.22

with no luck with any of them. i also tried 5.3.29 but still not working


Any idea what to do?
I havent changed anything in the shop during this time. and was not able to find any topics like this recently

screenshot upload: the image my client sent me
screenshot backend: my message when i upload


php log says this:
PHP Notice:  Undefined index: virtuemart_media_id in [...]/administrator/components/com_virtuemart/models/media.php on line 320 [...]
but not sure if it is before or AFTER the page-load that comes after each upload