ERR_NGROK_7185: The JWT Validation signing key source has an invalid additional jku: JKU is not a valid URL - ngrok documentation

What does ERR_NGROK_7185 mean?

ngrok returns ERR_NGROK_7185 with this message:

The JWT Validation signing key source has an invalid additional jku: <JKU> is not a valid URL.

Where can I get more help with ERR_NGROK_7185?

Email support@ngrok.com and include the error code.