In http://www.contactor.se/~dast/svn/archive-2003-07/0886.shtml Mike Wilcox reports a backtrace ending like this, both with a (single-component) --trunk option and without: File "cvs2svn.py", line 1481, in copy_descend dumper.copy_path(src_path, parent_rev, copy_dst, val) File "cvs2svn.py", line 932, in copy_path entries) File "cvs2svn.py", line 632, in change_path for ent in new_val.keys(): AttributeError: 'NoneType' object has no attribute 'keys' He also said: Tentatively, this crash would seem to be caused by the recent 'tag' changes, as this part of the repository has been converted successfully before, when 'only' the 'branch' code had been created (sorry, using the word 'only' to describe the branch-handling code seems kinda lame :-) ). I'd say it worked in revision 6372, but doesn't in 6455. I can provide, privately, the files that cause the problem; I can narrow down the behavioural change to a better revision than between 6372 and 6455; I can create a new issue, or tag some details onto #1409. Let me know if any of these are useful :-) I asked for the reproduction data, and he sent it to me, sorry can't post it here of course. I'll try to construct an untainted regression test based on it.