Fix Windows Phone 8/8.1 backup error

So you want to make a backup of your phone settings, apps or whatever, in the way Microsoft calls 'manual', which is entering backup > app+settings and pressing 'back up now' and you get the stupid error 'There was a problem backing up your settings. Try again later'.

Picture stolen from Microsoft Support forum

The old trick of deleting the old backup worked once but not anymore?

Here is the fix:

You have a buggy version of Windows Phone and you have to update it in order to back up without the error.

Probably your phone does the backup OK and you can find it browsing with the computer the Onedrive website. You'll find a backup with the date of your last 'erroneous' backup in the proper section of the web.

So check for phone updates and proceed. Don't worry for data losses, your data will be back after the update despite of backup error.