Troubleshooting agent updater missing json data

Owned by Sebastian Kirchmeyer
Last updated: Dec 11, 2023 by Matthew Hierholzer

This article helps troubleshoot a "Missing json data" error while using the agent updater.

LAST TESTED ON CHECKMK 2.0.0P1

Table of Contents

Problem

You try to register the agent updater (cmk-update-agent register or check_mk_agent.exe updater register), and you see the following error message:

Response without json Content-Type
 Unexpected answer from Checkmk server: Missing json data. Maybe we are talking to an agent bakery from before Checkmk 2.0 ?

Reason

You are actually talking to a site before Checkmk 2.0

The error message might be entirely correct, and you are talking to an old site.

The user you are using has an expired password

Another reason for this error message might be that the account you are using during the registration currently cannot log in to Checkmk, and you must change its password.

The requested agent package is unsigned

This can also happen when the updater usually runs, not only on registration.

Solution

You are actually talking to a site before Checkmk 2.0

Find the right site, or update the one you are talking to, if it is the correct one.

The user you are using has an expired password

Go to your Checkmk GUI and try to log in with the credentials you used during the registration process. If you are asked to change your password, repeat the updater's registration afterward.

Screenshot displaying the Change password screen. This page has multiple fields including Current password, New password, and New password confirmation.

The requested agent package is unsigned

Check if all agent packages are signed correctly. If not, bake and sign the agents in the agent bakery and retry the update or registration.