Always get an error when accessing the openHAB REST API with 2.4.0-snapshot #1389

I am always getting the following error when I acces the REST API:

{"schemaValidationMessages":[{"level":"error","message":"Can't read from file http://rpi3.karnsfamily.org/rest/swagger.json"}]}

Is this a known bug?

Did you try adding the openHAB port?

http://rpi3.karnsfamily.org:8080/rest/swagger.json

I have port 8080 accesses forwarded to port 80, but I get the same result when I access port 8080. I get this:

I have searched for the file swagger.json under /var/lib/openhab2, but it is nowhere to be found.

that is correct