Proxmox - Restore backups problem

Lately we've been unable to restore backups in Proxmox. It doesn't seem to be specific to a particular backup, and I've had the same problem with restoring any of them. I have plenty of space on the local system for the tmp directory - for example, the most recent backup I've tried is 9gb, and the Proxmox server I'm restoring to has 88 GB free in the root partition. The Proxmox console produces this error: TASK ERROR: command 'lzop -d -c /OSISOs/dump/[login to view URL]|vma extract -v -r /var/tmp/[login to view URL] - /var/tmp/vzdumptmp10495' failed: unable to create image: got lock timeout - aborting command When I try this on the command line, I get the following output: # lzop -d -c /OSISOs/dump/[login to view URL]|vma extract -v -r /var/tmp/[login to view URL] - /var/tmp/vzdumptmp10495 CFG: size: 372 name: [login to view URL] DEV: dev_id=1 size: 68719476736 devname: drive-ide0 CTIME: Sun Jan 21 00:59:51 2018 ** (process:11575): ERROR **: unable to open fifo /var/tmp/[login to view URL] - No such file or directory Trace/breakpoint trap This doesn't make any sense, because the directory /var/tmp/vzdumptmp10495 does indeed exist. If I remove it and try to start again, I get the same error. ---------------------------------------- I did find: It looks like an update to `lzop` has deprecated the '-r' switch. It's certainly not in the man page. Removing that switch and option from the command line allowed lzop to restore the file in question. Which is odd, because this works fine in a completely different Proxmox server (also v 4.2-2), and the version of lzop is the same - v1.03-3.