Restore stuck not doing anything

[hostingnuggets]

Hello,

I am trying to restore a dump of a memcached 1.5.22 server. The dump works perfectly but the restore just gets stuck and does nothing as you can see below:

$ ./memcached-util --addr 10.0.0.101:11211 --op "restore" --filename "mem_backup.json"
2021-07-15T15:18:28.516256 main ▶ INFO 001 address 10.0.0.101:11211
2021-07-15T15:18:29.206551 restoreCache ▶ WARNING 002 Key  already expired, skipping ..

On the server side with verbose mode in memcached enabled I see the following:

Jul 15 15:18:28 server systemd-memcached-wrapper[705468]: <27 new auto-negotiating client connection
Jul 15 15:18:29 server systemd-memcached-wrapper[705468]: 27: Client using the ascii protocol
Jul 15 15:18:29 server systemd-memcached-wrapper[705468]: <27 set  0 -553 0
Jul 15 15:18:29 server systemd-memcached-wrapper[705468]: >27 ERROR
Jul 15 15:18:29 server systemd-memcached-wrapper[705468]: <27
Jul 15 15:18:29 server systemd-memcached-wrapper[705468]: >27 ERROR

The backup itself seem to have worked correctly:

2021-07-15T15:03:33.822166 main ▶ INFO 001 address 127.0.0.1:11211
2021-07-15T15:03:34.351171 backupCache ▶ INFO 002 87676 values found in the storage
2021-07-15T15:03:38.374375 backupCache ▶ INFO 003 Output file successfully generated at: mem_backup.json

Any idea what's wrong?