Post-processing of the image failed – WordPress error.

Recently, I have come across a sporadic issue while uploading images in WordPress. The error, which occurs every now and again, reads as follows:

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.

Although the error message is pretty straight-forward, it seems as though there is something else at play here. I say this because of a number of reasons:

  1. On more than one occasion, the error has appeared while I was uploading small images. I’m talking about 700px images that were less than 100kb in size. Furthermore, I wasn’t uploading multiple images. This error occurred while I was uploading a single image.
  2. My server wasn’t busy at the time. I had a load average of 0.01, which is nothing. For those of you who don’t know, that basically means that my server’s CPU was sitting on a sun lounger sipping cocktails. Similarly, over half of the server’s memory was still free.
  3. My PHP installation has a healthy amount of memory dedicated to it. Not that it really needs much, considering how much caching is in place.
  4. There was no trace of anything in the error logs.
  5. It seems as though this issue has only started happening with WordPress 5.5.

To sum it up, my server was fine.

How I “fix” this issue.

The “fix” also leads me to believe that the error message isn’t correct. For me, I was able to get around this problem by pressing “Save Draft” and trying again. Once I press “Save Draft” and the page reloads, this error goes away.

To me, it seems as though the error is wrong and that another bug is causing it to be shown.

Anyway, hopefully this post saved one or two of you from wasting your time and money on moving to a better server. Let us know if the “Save Draft” trick works for you.