Date field erroring

We recently upgraded our Kirby version to 3.5

Since then our date field in the articles is giving an error but i don’t understand why:

Here is the yml which hasn’t been changed since updating and used to work before:

                type: date
                time: true
                default: now

Removing the date which was present from before in the .txt file doesn;t seem to help

Any advice appreciated, thank you

From which version did you upgrade? Did you do all the usual things like clear media folder, sessions folder, cache folder and browser cache?

I upgraded from 3.3.3 to a few weeks ago, i followed all the instructions at the time for media folder etc