same things happens to me on jenkins v 1.399

I would be willing to provide a patch for this, given that someone can point me in the right direction.

This is actually caused by a bug in the Stapler library with how it handles exported Map properties. Basically, it uses the String representation of a the key for each entry in the map. Sometimes (as is the case with the git plugin), the key contains characters which are not valid XML. In this specific instance, the problematic map is the buildsByBranch map found in the hudson.plugins.git.util.BuildData class. The key of the map is the name of the branch, which often contains slash (origin/master). Of course "/" isn't a valid character in a Tag name.

However, it looks like Kohsuke just released a new version (1.160) of Stapler which adds a new option to the @Exported annotation (verboseMap) which allows for switching on a more verbose, but safer mechanism for exporting maps.

I suggest upgrading to the 1.160 release of Stapler, and modifying how the buildsByBranch map is exported to use the new property. Maybe something like:

@Exported(verboseMap="branch/build")
public Map<String,Build> getBuildsByBranchName()

Which will generate XML similar to (I think):

<buildsByBranchName>
<branch>origin/master</branch>
<build><!-- build XML here --></build>
</buildsByBranchName>
<buildsByBranchName>
<branch>origin/topic-branch</branch>
<build><!-- build XML here --></build>
</buildsByBranchName>

For more details on the new attribute, consult the Stapler 1.160 Javadoc.

Looking at the 1.160 stapler source, it will now actually adjust the element names to be valid:

http://java.net/projects/stapler/sources/svn/revision/1738

Using the verboseMap property is likely preferable in many cases, but simply updating to 1.160 should resolve the malformed XML issue.

Looks like this issue was reported again under JENKINS-8988 and fixed. Should this one be resolved as a duplicate?

Consolidating to JENKINS-8988. Fixed in 1.405.

JENKINS-8988 is going to be fixed in 1.405...which should fix this as well.