Failed to register pmm-agent on PMM Server: Internal server error

Percona Monitoring and Management (PMM) PMM 2.x
6

looks like your DB scheme was upgraded to version newer then 2.32.0, have you upgraded and then downgraded your PMM Server? Because of new constraints in PMM Server DB introduced in newer version of PMM it can’t write new record to DB.

There are 2 solutions:

  1. Upgrade your PMM Server, so it can handle new constraints correctly
  2. Downgrade DB scheme using reverse engineering