SyntaxError: Unexpected token < in JSON at position 0

[Example2053]

Hello
I have a problem when login with database connection.
I am connecting to a MongoDB using Custom Database. The query of this database is working fine when I use the “Try” button.
However, when I use the “Try Connection” tab, Auth0 is throwing this error:
{
“error”: “access_denied”,
“error_description”: “Unexpected token < in JSON at position 0”
}

It is the same error that I am getting in my web application as error 500.

Would you give an advise to fix this problem?

May the problem be in the authentication server or did I forgot to activate something?

[Example2053]

My problem was a misconfigured rule.

[konrad.sopala]

Thanks a lot for letting us know! Glad you have figured it out!