GIT pull error - remote object is corrupted

As Julian said see https://confluence.atlassian.com/display/FISHKB/Git+indexing+fails+due+to+bad+pack+header

It really can be a memory issue, and to make sure we don't lose the solution here it is:

git config --global pack.windowMemory "100m"
git config --global pack.SizeLimit "100m" 
git config --global pack.threads "1"

Adding git config --global pack.window "0" worked for me...along with following

git config --global pack.windowMemory "100m"
git config --global pack.packSizeLimit "100m" 
git config --global pack.threads "1"

Reason:

Git clone compresses the data while cloning the repository

It compresses the data on the server memory before receiving the data/files.

If the server has out of memory you will get the above error while packing the objects

You can fix the issue by making git clone the repository without packing the objects on the server with the following.

git config --global pack.window "0"

It appears the answer is in the comments: git fsck

Just got this error, and spent half a day doing all the things described in the post : fsck, repack, gc, configuring memory options.

Also followed this post : http://git.kernel.org/cgit/git/git.git/tree/Documentation/howto/recover-corrupted-blob-object.txt?id=HEAD

But in the end, it was as simple as finding the damaged object(21f3981dd35fccd28febabd96f27241eea856c50 in this case) in the bare repository and replacing it with the non damaged version(which can be found in the .git folder of any of the local repositories which pulled/cloned from the bare repository.)