Time Machine can't create a local snapshot

From the terminal, look at Time machine local snapshots:

tmutil listlocalsnapshots /

# tmutil listlocalsnapshots

com.apple.TimeMachine.2017-09-30-071340 (dataless)

com.apple.TimeMachine.2017-09-30-091235 (dataless)

com.apple.TimeMachine.2017-10-05-084406

/

See if you have any dataless snapshots in the list. IF so delete them , here is an ex from the above list.

sudo tmutil deletelocalsnapshots 2017-09-30-071340

and

sudo tmutil deletelocalsnapshots 2017-09-30-091235

Hi,

Do you backup on your local disk? It's a tad dangerous for critical backups. Better to use an external disk (or a Blackmagic MultiDock 😉).

There is two different things in snapshots, there's the local snapshots that are dependant of the APFS file system (you can see the detail of what they do by opening Time Machine preferences: "Local backups as space permit, etc.") and there are Time Machine main backups. Time Machine rely on hard links to perform these backups and consequently cannot use a APFS formatted disk to do so, one must use a HFS+ formatted disk... (it's usually here that I feel obliged to remind: users cooperative forum here, nobody from Apple... 😕).

Regards.

Maybe Time Machine attempts create a local backup because it cannot contact your usual network backup. But I imagine you have already checked your network connections...

I imagine not a chance either for the distant disk be full up to the brim...

Is this local (certainly APFS indeed) problem the only one? You manage to backup with TT normally to your distant disk?

https://support.apple.com/en-us/HT202784