Problem with uploading certain pictures

Hi everyone,

I have a problem with uploading and I can’t seem to find a solution for it. Hopefully you can help me.

Yesterday I tried to upload some pictures to an existing Envira gallery. With one of them, there was a blank space instead of the thumbnail and the picture wasn’t visible on the website. I added 9 more pictures and 3 of them had the same problem.

To solve the problem, I tried to upload the same pictures to the media library, but this doesn’t work either. If I try, I get this message ‘The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later’.
The weird thing is that only these pictures have this problem. If I try to upload a different file, everything works fine.

To solve the problem I’ve updated WP and the envira plug-in, I renamed the file and saved it in another folder on my computer, but none of this helped.
It’s a .jpg file, the size is only 163kb and the color space is sRBG, so that can’t be the problem either.

Has anyone any idea what could be wrong?
Thank you very much for your help!!

Cheers Marlonneke