To avoid this type of error, you can modify your images before you upload them. It will help you uploading error free images. WordPress recently updated their requirements on media file uploading in server.
If you experienced the error message "Post-processing of the image failed. If this is a photo or a large image, please scale it down to 2500 pixels and upload it again", you should watch the video carefully.
There is no exact solution of this error, but we can try to solve the issue implementing some techniques. This will help you editing and updating the issues effectively. You will able to handle the error following some common tricks.
The problem happens for browser caching that you can easily fix clearing the browser cache files. You can also upload images from the Media Library option and the problem will be fixed. I experienced the same issue on my website after the WordPress Version update and did research on it.
Finally, I got a solution and I created the video to help more people who is experiencing the same issue on their website. I know how you feel when you can't upload images on your website and you don't get any solution.