Hello, I am getting the same error, however, I am not using Avast antivirus but a different one.
Disabling my antivirus program and/or adding the offending directory to the exceptions list doesn't make the error go away.
The game worked fine until I tried to play Yland 17 when it crashed. After that the error started to appear.
[edit]
To clarify: I just added ./Ylands/Launcher/ to the exception list because I couldn't find a directory or file called 'tmp' anywhere in any of the subdirectories of that directory.