Strange problem upload images for non administrator

Hello,

i have a strange problem on my website.

While administrator can use and upload images as it should using media libray.

All others users can’t. For example if an editor try to upload image it get this error:

Post-processing of the image failed likely because the server is busy or does not have enough resources. Uploading a smaller image may help. Suggested maximum size is 2500 pixels.

But the same time if an administrator try to upload the same image it can do it normally.

Please advice.