Time machine problems

For the last three days, my Time Machine has refused to backup. It says there's an error copying files. I've checked the disk in Disk Utility, no issues, I've used a different disk, a different interface and cables. It's absolutely the same error each time and I can't pin point anything that has changed at that time.

The error I am getting varies slightly but the two elements in bold are always present. When it started it was just those two errors but more recently other errors have crept in amongst them. There's no mention in Console of any file error or copying error.

I can find no reference on the net, with the exception that DirtyJetsam refers to IOS technology. There's no IOS device connected and even with my phone (on the same network) in Airplane Mode the result is the same.

Any clues gratefully received.

Nov 20 09:03:10 MacBook-Pro kcm[3517]: DEPRECATED USE in libdispatch client: Setting timer interval to 0 requests a 1ns timer, did you mean FOREVER (a one-shot timer)?; set a breakpoint on _dispatch_bug_deprecated to debug

Nov 20 09:03:11 MacBook-Pro com.apple.xpc.launchd[1] (com.apple.imfoundation.IMRemoteURLConnectionAgent): Unknown key for integer: _DirtyJetsamMemoryLimit

Nov 20 09:03:19 MacBook-Pro diagnosticd[913]: allowing Console (3521) access to stream due to admin status

Nov 20 09:03:19 MacBook-Pro diagnosticd[913]: send_stream_request_block_invoke: connecting to streaming server

Nov 20 09:03:19 MacBook-Pro diagnosticd[913]: Posting stream filter: "{

global = 30064771083;

}"

Nov 20 09:03:19 MacBook-Pro diagnosticd[913]: System mode client started - Console (3521) - mode: 0xb, filter: "<empty>"

Nov 20 09:03:22 MacBook-Pro com.apple.xpc.launchd[1] (com.apple.imfoundation.IMRemoteURLConnectionAgent): Unknown key for integer: _DirtyJetsamMemoryLimit