Create 2 managers: one active manager, the second is passive (m1, m2)
Steps to reproduce:
1. Remove the active manager from the cluster (now the passive manager takes leadership - m2)
2. Create third manager (m3).
3. Connect the manager and join him to the cluster (which now m2 is the active manager)
The error I got is "500 internal server error"
Also, the case was reproduced only when I removed the active cluster.