Domoticz

Since some time my system couldn't be found, and then I need to reinstall Raspbian and Domoticz again.

I used the beta branch for quite some time, but now, with the latest several releases the system doesn't work (first the appcache mention, then connection refused messages). So, installing everything again. Trying to restore a backup, but... since that is from a beta, it can't be used in a stable version, and after upgrading to beta we start again with the error-messages. Bought some new SD-cards, switched Pi's thinking it might be a problem there, but nope.

:frustrated:

Make sure your powersupply is stable and sufficient. Often a hidden source of problems.

Make sure it has 5volts (5.1 or 5.25 is even better) and can at least deliver 2A (or more when using a Pi4). Or more if you have multiple devices connected via USB, GPIO, etc.

Here running Beta’s for long time, no real problems. Yes, sometimes something brakes with a new Beta but usually fixed soon in a next Beta. But that is the trade off with running Beta, new functionality sooner but also a change of small issues

Also check the following wiki page for some troubleshooting tips:
https://www.domoticz.com/wiki/Troubleshooting

Perhaps you should take a look at running Domoticz in a Docker container.
Very easy to make a backup and restore a previous versions if a new Beta does not properly run.

It literally takes me less than a minute to revered back to a previous Beta if the new one sucks

(If you have a very complex customized Domoticz system then Docker might not be the solution for you, but for most Domoticz setups it can be really handy to run it in a Docker container.)