I have a repo that I have been committing for 2 months. I do not seem to get any error when I commit daily. However I was looking at git logs and I see that first ever git log (or maybe git can't see beyond that log point) has an error message like this
:100755 100755 1948ac6... 2af905e... M document.doc"
error: Could not read 190d54eb3278746a4e35fd4be82689eb4b1d20a8
fatal: cannot simplify commit cb0c2a3bf0a4ad665eb376b818bdcb0652a06eec (because of 190d54eb3278746a4e35fd4be82689eb4b1d20a8)
I tried the recommendation on: https://git.wiki.kernel.org/index.php/GitFaq#How_to_fix_a_broken_repository.3F
But I did not get what I was trying to achieve, whatever was recommended did not help my case.