Server does not allow request for unadvertised object ...

git submodule update
error: Server does not allow request for unadvertised object df38cc27c972c837560936e0b53b1ba73a222ad7
Fetched in submodule path 'submodule-name', but it did not contain df38cc27c972c837560936e0b53b1ba73a222ad7. Direct fetching of that commit failed.

主项目中记录的submodule的HEAD超前，导致找不到指定的commit.

解决办法

push submodule_name origin master //submodule `submodule_name ` push
git submodule update