Class created by MakeClass() won't load because "error: invalid use of non-static data member"

So I have tree called “Delphes” and I load the library and do tree->MakeClass(). This creates the class and header files with the same name as the tree. If I then attempt to load the “Delphes.C” I get many “error: invalid use of non-static data member” errors, for all the variables used as array length.

I understand how to solve this error (add static before the variable definition), but it’s the first error of many and I suspect MakeClass() should make something that works (or at least loads) out the box?

Root is running in a singularity, the tree is the default one created by the madgraph tutorial. Attached is a full log of the process, it contains a few other warnings that may be related. MakeClass_error.log.txt (8.5 KB) it formats correctly if read with cat/head/tail.

Any pointers on where I should be looking for the ‘root’ cause of this problem?

Oh, Just updated the version of root from 6.06.08 to 6.14.06 and the error is gone. (Replaced with warnings, but if they prove a problem I will make a different question.)

Problem solved.