duplicated OMV extras in web gui & prereq_nginx_service_monit error after upgrade to OMV 5.4.2-1

I have updated my OMV 4 to the current version 5.4.2-1 with the following short instructions.

RE: OMV 5.0 - finally out! :-)

Afterwards I can log in to the Web-GUI, but there I see 2x OMV extras. One of them works, the other one generates an RPC error message. This error message also appears when I go to the System Information section.

Fehler #0:
OMV\HttpErrorException: RPC service 'OmvExtrasOrg' not found. in /usr/share/php/openmediavault/rpc/rpc.inc:100
Stack trace:
#0 /usr/sbin/omv-engined(537): OMV\Rpc\Rpc::call('OmvExtrasOrg', 'getStyles', Array, Array, 1)
#1 {main}

In the console I get an error message regarding 'omv.deploy.monit.services.collectd' with the omv-salt commands for nginx and phpfpm.

I have reinstalled both omextras and openmediavault with all plugins. I also cleared the GUI cache with omv-firstaid and also cleared the cache in my browser. OMV-Update did not solve both problems either. Nothing suitable is logged in the syslog.

What else can I do to make both problems disappear?

@ryecoaaron

No problem. Everyone reads over something. Especially if it sounds like a problem that has been mentioned several times.

Below is the list of installed packages. I had also searched it for duplicates, but found nothing.

ii  libopenmpt0:amd64               0.4.3-1                             amd64        module music library based on OpenMPT -- shared library
ii  openmediavault                  5.4.2-1                             all          openmediavault - The open network attached storage solution
ii  openmediavault-autoshutdown     5.0.4                               all          OpenMediaVault AutoShutdown Plugin
ii  openmediavault-diskstats        5.0.5-1                             all          openmediavault disk monitoring plugin
ic  openmediavault-jdownloader      3.2.3                               all          OpenMediaVault Jdownloader plugin
ii  openmediavault-keyring          1.0                                 all          GnuPG archive keys of the OpenMediaVault archive
ii  openmediavault-minidlna         5.0.4                               all          OpenMediaVault miniDLNA (DLNA server) plugin
ii  openmediavault-omvextrasorg     5.3.1                               all          OMV-Extras.org Package Repositories for OpenMediaVault
ii  openmediavault-wol              3.4.2                               all          OpenMediaVault WOL plugin

In which paths do I find the appropriate configuration files that are responsible for the RPC services? I would try to remove references to the old omvextras.org (4.x).

A note in passing: I originally started with OMV 3.x, then updated to 4.x without any problems and now when updating to 5.x these small problems occur.

Apart from the messages, OMV 5 works as desired. It would be great for me if I could eliminate the little things.

I have removed the OMV JDownloader plugin. Actually omvextrasorg.inc. still existed. I deleted it and restarted engined afterwards.

Then I emptied the cache of the Web GUI via omv-firstaid and also the local browser cache. The errors in the GUI still occur.

omv-engined -d -f

is without errors.

omv-salt deploy run nginx 

still returns the known error regarding OMV Monit.

Rendering SLS 'base:omv.deploy.monit.services.collectd' failed: Jinja error: Object of type StrictUndefined is not JSON serializable

What else can I do?