Sounds like something the bundled TWRP would say,
If you want to continue doing serious things with TWRP, I can only recommend installing TWRP 3.2.3-0, instructions (section “TWRP Install”) and downloads are here … Fairphone 2.
The bundled TWRP 3.1.1-0 is valid in its own right … it’s under the control of Fairphone and they make sure it delivers some basic functionality they want it to deliver in a certain way. But it’s old, doesn’t support encryption, and it can behave slightly differently than twrp.me TWRP in certain cases.
The current twrp.me TWRP 3.3.0-0 seems to have trouble with encryption, so I don’t recommend it, although I guess most people don’t care about encrypting their data on the phone, so it should work fine, too, in most cases.
If you got all your important data together in a safe place, installing from scratch is the cleanest approach to get a working phone.