Compatibility of root-files

On my new notebook, I’m using root version 5.12e (at the moment upgrading to f), which can read my old 4.00/08-files without a problem (even my TTrees with own classes are read). On my desktop computer. I still use the 4.00/08 version. Now I tried to open a new root-file with the old root-version, and get an error message: “R__unzip: error in header”. Is this normal behaviour and if yes, is there any way to convert the files?

This problem has been fixed in v5-12-00f
A simple work-around is to disable the prefectch cache:

where c is a pointer to your TTree or TChain.