Compilation error: StaticJsonBuffer is a class from ArduinoJson 5

[robintel]

Hello,

I have started from scratch, in Windows 11 and Ubuntu 18 LTS, with the latest Arduino IDE, as well as with Arduino IDE 2.1.1.

Compiling the code fails with:

"Compilation error: StaticJsonBuffer is a class from ArduinoJson 5. Please see https://arduinojson.org/v7/upgrade-from-v5/ to learn how to upgrade to ArduinoJson 7"

[PatKeel]

I have the same problem now. In the past it worked with my old win10 pc.