I have been backing up my macbook using the following command
rsync -avz --delete --exclude '.DS_Store' username@macbook.local:/Users/username/ /media/file-server/backup
It used to work like a charm, but recently I started to receive the following error:

ERROR: out of memory in receive_sums

rsync error: error allocating core memory buffers (code 22) at /SourceCache/rsync/rsync-24.1/rsync/util.c(120)

rsync: connection unexpectedly closed (6917462 bytes received so far) [receiver]

rsync error: error in rsync protocol data stream (code 12) at io.c(454) [receiver=2.6.9]

rsync: connection unexpectedly closed (2644674 bytes received so far) [generator]

rsync error: error allocating core memory buffers (code 22) at io.c(454) [generator=2.6.9]
Does anyone have a clue on how I can solve this issue?

I tried searching the forums and other sources, but so far I have had no luck.