When navigating certain functions in API portal, such as creating a new API key, you will receive the error: Plan could not be created/updated on the master server
Release : 3.5
Component : API PORTAL
This issue can occur due to a lack of space on the /opt volume
To check for large files on /opt you can connect via SSH and run
sudo du -a /opt/ | sort -n -r | head -n 20
Certain files commonly take up unneeded space such as patch (L7P files). Once the L7P was successfully applied these files can be safely removed to clear up some space.