You should not ask for help in Bugzilla. It's meant to  report clear bugs, which this doesn't seem to be. Help for deployment can be commercial support. 
This looks like user problem, not LO. I set Needinfo for you to solve this yourself.

So are you trying to upgrade an older LibreOffice installation *also deployed using GPO*? If so, you need to describe *in detail*, how you upgrade:

* What GPO feature are you using for deployment: e.g., that could be a startup script, or software installation policy;
* Are you re-using the same GPO, or are you creating a new GPO for the new MSI;
* What did you do with tour older deployment: remove with uninstall? simply remove?
* If you delete old policy, does it have a "delete from user systems when out of scope" (or a similar) property?
* Which is the new LO version, which was the older version, and was there an even older version also deployed using GPO?

Basically, the problem is most likely that you do not remove the older deployment policy from user systems - and the *GPO* restores the registry key after LO installer has removed it. I suspect that actual sequence is this:

1. You install LO version e.g. 5.0 using GPO.
2. You deactivate 5.0 without uninstalling from user systems, and deploy 6.0; this works fine, with LO installer detecting LO 5.0, uninstalling it, and installing 6.0.
3. At some point, user systems get rebooted, and get old policy re-activated from cache, getting additional registry key from older GPO for LO 5.0 re-applied.
4. You deactivate deployment for 6.0, and deploy 7.0 - and that fails, because user systems now have registry settings as if there are *two* simultaneously installed LO versions: 5.0 and 6.0, which confuses installer for 7.0.

Okay I try to make it more clear here,

First I'l like to answer your questions.

* What GPO feature are you using for deployment: e.g., that could be a startup script, or software installation policy;

> We are using software installation group policy. Not a script or modification.

* Are you re-using the same GPO, or are you creating a new GPO for the new MSI;

> We're not creating a new gpo. We have one Group Policy for the computers group in an ou.


* What did you do with tour older deployment: remove with uninstall? simply remove?

> When you add under software installation the newer libreoffice package which assinged with the right local code a window popup ask for "assign" or "expanded" under the property "update" you can select package which is to update.

There are also 2 options: First in this softwareinstallation window ask for:
- Uninstall old package and install newer one
- package can installed over the installed one

One thing here, I didn't notice that this window automatically select "Uninstall old package and install newer one" instead of "package can be installed over the installed version"

So that this GPO automatically under properties set "uninstall and install newer package" we run into this that regedit entries are not deleted. 

* If you delete old policy, does it have a "delete from user systems when out of scope" (or a similar) property?

> We didn't delete by updating the older package, and don't touch the listed older one direclty.
After time when all clients got the update we can remove this how you said and tick that users can use the programm. (So that it is not deinstalled after out of scope"

* Which is the new LO version, which was the older version, and was there an even older version also deployed using GPO?

> We tried to update from 7.0.6 update to 7.1.5.
in the past the same was happend with latest 6er versions.

I thing the problem here is the gpo uninstalling process, I need to check it also which the option that the package can be over installed , so that the gpo does not first uninstall the old one. This I had first seen yesterday.

But it should also work when the gpo uninstall a older one  first or not?


Perhaps you can reproduce this.

My handling here was on a VM like this:

1. Deploy LibreOffice 7.0.6
> Grouppolicy -> Computerconfiguration -> Deployment -> select libreoffice.msi

2. run gpupdate /force /boot

3. After reboot libreoffice is installed

4. Update
Navigate through the path Computer Configuration\Policies\Software Settings and right-click Software installation. Select New –> Package:
select Libreoffice to update.

Window ask for assing or expanded settings where I add under the update tab the older libre office package like I said.

This steps are the only steps I did.


I'll test it with the setting that a newer package can be installed over an existing one without uninstalling, perhaps this will working. 

But first thanks for your answer here and wish a nice weekend,
best Regards and Greetings