Errors are quite common and can occur without any warning. But when you diagnose the exact reason behind the error code, you can quickly fix it with the proper solution. When it comes to the Avast antivirus error code 42040, it may happen during runtime. When the program fails to run or crashes during runtime, you will end up with this error code. The reason behind the error might be conflicting programs, virus infection, or insufficient memory. Continue to read the following sections to fix the avast antivirus error code 42040.

Close the conflicting program
Step 1: When programs conflict with each other, you will end up with the 42040 error code during runtime. You can fix it by closing one of the programs. In the first place, you need to know which programs are the conflicting ones.
Step 2:Press the Ctrl, Alt, and Delete keys simultaneously to open the Task Manager.
Step 3:Close the running programs one by one. Whenever you close a program, check whether the error code has disappeared.
Step 4:When you identify the exact program which causes the error, uninstall it from your computer and check whether you have resolved the issue.