Error "Failed to get the RPC parameters"

Hi guys,

yesterday I installed OMV 3.0.86 on my machine and upgraded it to 3.0.88 several times. On version 3.0.86 as well as on 3.0.88 I continuously get errors "Failed to get the RPC parameters." First intention from my side was that I have some wrongly configured DNS-service running in my network but it turned out that I'm currently using the DNS-servers provided by my ISP only. So I don't get what might be the problem.

Does anyone have some hints what I can do to identify the problem?

Thanks in advance.

Here we go:

Fehler #0:
exception 'OMV\Rpc\Proxy\Exception' with message 'Failed to get the RPC parameters.' in /usr/share/php/openmediavault/rpc/proxy/json.inc:47
Stack trace:
#0 /var/www/openmediavault/rpc.php(45): OMV\Rpc\Proxy\Json->handle()
#1 {main}

I just tried to observe if it is reproducible somehow but that error occurs sporadic after some minutes when using the surface.

Addition:
It turned out that the server responds with a HTTP-state 400 but still no joy in reproducing it constantly.