New KeePassRPC.plgx plugin 1.11.0 problem

This problem is caused by the new KeePassRPC.plgx (1.11.0). I put two older versions of KeePassRPC.plgx back, but the error is the same. I do not understand. I didn’t change anything in KeePass’s settings. The KeePassRPC.plgx plugin 1.11.0 was still working yesterday. Windows 10 2004 and Firefox 78.02, Kee Firefox plugin v3.2.7 Communicate with KeePass using this TCP / IP port 12546 is enabled.

What should I do? Please help me!

I guess some other instance of KeePassRPC blocks the required port.
You may run more than one KeePass on your machine.
If this is the case every one needs an other port.

No, only one instance is running. There is only one Keepass installed on your computer and there is only one copy of “KeePassRPC.plgx”.