I keep getting this error on specific posts that is created using custom post type. the server is busy or does not have enough resources. Uploading a smaller image may help. Suggested maximum size is 2500 pixels. Some post of the same custom post type doesn't have this error but some does. These are the steps that I have considered so far: Themes & plugin testing - I turned the plugin on/off to see if there are any changes but I still keep getting the error I have uploaded a small image less than 500kbs but I still got this error message.