the memory limit is already at 128.

At this point I would contact my hosting provider (since smaller images can be uploaded).
Quite possibly the memory limit is overridden by your host's settings.

Hoster did just to test push to 512 (knowing it would not help) and yeah unfortunatly it did not.

Other components are working fine. big components have been installed without any problem. Also the SIGallery Pro can upload big pictures without any trouble.

There must be something wrong with the image for K2 only. Can you perhaps test that issue on your side? use a jpg 3000 x 1000 and see if you can upload it. with a J 3.3 and a 2.6.8 or dev 2.7 ?

SigPro does not perform the resizing that K2 does.
It is not only uploading the image it is also creating 6 new ones.

yes i know and the 6 images are generated. it means when i refresh the browser going back to my item i see the message item succesfully updated and if i look the script has done the job and the resized pics are there.
so the question is what is causing the error 500... my hoster has no clue. i have no other server to test for now.

Whathas your error_log recorted?

there is nothing in the log. error on all switched to on does not give any clue either. this is really weird.

No, I mean the physical file. error_log.
Apache's (or your user's) logs.

If you cannot locate it, then your hoster can help you.
Once you have opened it, disregard any notices or warnings and look for Fatal Errors.

thanks for the help Krikor unfortunatly my hoster is not able to help and has no clue. there is nothing to find in the log. I love the new design of K2 btw! really enjoy it. great work guys!

Thanks Laurent.
Sorry about the issue.

Last hint. If you have ssh access take the time to see how you can tail apache's error log.