Running `git submodule update` after commenting out the url setting in both .gitmodules and the corresponding section for the submodule in .git/config results in a segmentation fault instead of a suitable error message. The cause is `sub->url` being NULL here (actual segfault comes a couple calls further): https://github.com/git/git/blob/9e49351c3060e1fa6e0d2de64505b7becf157f28/builtin/submodule--helper.c#L2027 Possibly relevant: a similar snippet is being properly protected against null-pointer dereferencing here: https://github.com/git/git/blob/9e49351c3060e1fa6e0d2de64505b7becf157f28/builtin/submodule--helper.c#L1243
