WordPress error on image upload “Post-processing of the image failed likely because the server is busy or does not have enough resources”

This usually means that you don’t have the fcgid PHP module installed or enabled. To do this on Ubuntu Linux under Apache2, you need to do the following steps:

1. install fcgid

sudo apt-get install libapache2-mod-fcgid

2. enable fcgid if the install doesn’t enable it

a2enmod fcgid

3. install imagick if not already present

sudo apt-get install php-imagick

4. done!