The problems with custom apps and programs such as a2billing are killing me. How do I uninstall 2.4 and go back to 2.3???
you don’t, but there is nothing fundamentally different with custom apps or how you might be interfacing with a2billing that has changed from 2.3 to 2.4 - you should be able to do what ever it is you were doing in 2.3 - try posting to the forum the details and maybe someone can help you.