Time Machine completed a verification of your backups on “Time Capsule”. To improve reliability, Time Machine must create a new backup for you.

Hi

As per title - since upgrading to Sierra i have been getting the error.

Time Machine completed a verification of your backups on “Name of Back Up Drive”. To improve reliability, Time Machine must create a new backup for you.

If i select 'Start new back up', it takes about 24 hours to make first back up, backs up once or twice more then i get the error again.

iMac is connected to time capsule by gigabit ethernet cable.

I don't believe it can be a hardware fault as i alternate back ups between Time Capsule and a Synology NAS

and get the same problem with both. (This worked fine for at least 18 months prior to Sierra)

I know other people have been having this problem and its been suggested that the cause is anti virus software - i don't have any Anti Virus Software installed.

I have about 1.5TB of photos and videos on my iMac so being without reliable backup is pretty stressful - so any steers towards how i might solve the issue would be much appreciated!

Thanks