A serious bug in ROOT was found which could influence the version management of the parameter handling in FairRoot. The problem was caused by change in the function TKey::GetCycle() in ROOT. This problem effect only people saving multiple versions of a parameter in the same parameter file. When getting back the parameter from ROOT file there was a mismatch in the versions. If only one version of a parameter is written to the ROOT file or if the differents versions of the parameter don't differ in the content the problem don't show up. In these cases one get the correct parameter container.
The issue is already fixed in the ROOT source code. We have extracted the needed changes to the ROOT source code and have implemented a dedicated patch for our last FairRoot releases. To get the new code please install on of the following patch versions for the releases jul14, dec14, or mar15.
The latest patch release are jul14p4, dec14p1, and mar15p2.
It is highly recommended to install one of the three patch releases. Older versions of FairSoft will not be patched.