When running repo sync error: Exited sync due to fetch errors

Ok, so thanks for the effort, I found a similar question here

Summary:

Invoking $ repo sync -f -j10 did the trick.

As it seems -f or --force-broken flag allows it to recover from network error and more important recover on broken/missing objects.

repo sync -j1 -f --force-sync

fixed my cm13.0 sync error