Shelly smart plug-S trouble (EU)

Hi! I’m struggling to get Shelly Smart Plug-S into Home Assistant. First, I did not update them to the latest firmware version. when i finally got around to it I get an error when i try to load them. I have tried both normal integration and the integration via HACS. The plugins work well with the Shelly app. Here is the error code I get:

“Configuration flow could not be loaded: 500 Internal Server Error Server got itself in trouble”

Anyone who has any idea how to make this work? (Attached picture with the text is on Norwegian)