Difference between Keycloak 16.1 and 12.0.4: "Invalid client credentials" for public client while the same request works without problems for 12.0.4

A Postman Request to Keycloak with public client ID and username and password worked without problems in Keycloak 12.0.4. The same request with the same configuration in keycloak now returns following error:
“error”: “invalid_client”,
“error_description”: “Invalid client credentials”
Can you tell me, what I did wrong?

You will be very kind if you provide reproducible example: so that request and client configuration.

This is the postman request:
2022-01-13 17_46_28-Postman

This is the client configuration:

Public clients have had secrets before :shushing_face:. That issue was fixed [KEYCLOAK-14840] Public Client Representation includes a secret - Red Hat Issue Tracker. :man_shrugging: I guess client is not properly migrated in Keycloak 16 or it doesn’t handle old buggy client state correctly.
I would say, delete that client and create it again from the scratch and you should be fine.

Thank you very much. I finally found the issue. I had a small typo in the client ID by swapping two characters. I finally spotted my mistake.