None of your pictures (...) uploaded successfully- help

I used to upload pictures without any difficulty.

I haven't reached the limit.

I repeat the same procedure I've done many times - same result.

Recently there was an issue where some kind of bug entered the system but I removed it.

Then recently, I tried to go to an html page of pictures. It links to pictures from the gallery. The pics were empty. Only frames.
But I had uploaded a few new ones. I noticed that there was a new inscription in the html address of each pic: a2 (album 2?). I manually changed the html of each pic - the empty ones - until they had the a2 mention in the same spot as the others. They all appeared.

Since then, I haven't been able to upload new pictures.

Can you help?