diff --git a/Annex/Fixup.hs b/Annex/Fixup.hs
index 37cbe8f63a..38cb676a1c 100644
--- a/Annex/Fixup.hs
+++ b/Annex/Fixup.hs
@@ -93,8 +93,8 @@ fixupUnusualRepos r@(Repo { location = l@(Local { worktree = Just w, gitdir = d
 	| needsSubmoduleFixup r = do
 		when (coreSymlinks c) $
 			(replacedotgit >> unsetcoreworktree)
-				`catchNonAsync` \_e -> hPutStrLn stderr
-					"warning: unable to convert submodule to form that will work with git-annex"
+				`catchNonAsync` \e -> hPutStrLn stderr $
+					"warning: unable to convert submodule to form that will work with git-annex: " ++ show e
 		return $ r'
 			{ config = M.delete "core.worktree" (config r)
 			}
@@ -102,8 +102,8 @@ fixupUnusualRepos r@(Repo { location = l@(Local { worktree = Just w, gitdir = d
 		( do
 			when (coreSymlinks c) $
 				(replacedotgit >> worktreefixup)
-					`catchNonAsync` \_e -> hPutStrLn stderr
-						"warning: unable to convert .git file to symlink that will work with git-annex"
+					`catchNonAsync` \e -> hPutStrLn stderr $
+						"warning: unable to convert .git file to symlink that will work with git-annex: " ++ show e
 			return r'
 		, return r
 		)
diff --git a/doc/bugs/warning__58___unable_to_convert_submodule_to_form_that_/comment_2_7f4800ee68c98606bc8a3ce959646014._comment b/doc/bugs/warning__58___unable_to_convert_submodule_to_form_that_/comment_2_7f4800ee68c98606bc8a3ce959646014._comment
new file mode 100644
index 0000000000..723169a9b4
--- /dev/null
+++ b/doc/bugs/warning__58___unable_to_convert_submodule_to_form_that_/comment_2_7f4800ee68c98606bc8a3ce959646014._comment
@@ -0,0 +1,20 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 2"""
+ date="2021-01-19T16:14:38Z"
+ content="""
+Hmm, that happens if it somehow gets an exception while fixing up the .git
+file and unsetting core.worktree in the git config. I've modified the code
+so it now will display the exception as part of that message.
+
+If by "get for every file" you mean the same run of git-annex is displaying
+it repeatedly, that would be weird -- it's run in early startup not later.
+
+One way I can see this failing is if core.worktree is not actually set.
+Then unsetting it would fail and it would display this message. But it
+would not even try to unset core.worktree unless something tells
+git-annex that the git directory is located under the parent repo's
+.git/modules/ Despite the `git rev-parse` you show, something is
+making git-annex still think that is the case. Likely because .git
+is not a symlink.
+"""]]