OH3 first steps don't work

I have just migrated from OH 2.5 to 3.0. Things, items are still there! Locations and Equipment groups like heating and security are missing.
I tryed to create them in the model section but had no success.
Where an how can I create locations and equipment groups and add the existing things and items to them and keep there names? It was a lot of work to define them.

Can you elaborate on this? What does “no success” mean? Got any configurations or screenshots to show?

For example: In OH 2.5 I have the thing “Büro Klima” with the location “Heizung” After update I didn’t have the location “Heizung” in OH 3.
So I created the location Heizung in OH 3 an added equipment from thing “Büro Klima”
In OH 2.5 I have the Item “Büro Klima Innentemperatur”. While adding the equipment to the location Heizung I could only select item indoor temperature. I could not add the Item 'Büro Klima Innentemperatur".

Please show us your thing and item configs of both, oh2.5 and 3.0.
Without those information, it is nearly impossible to see what‘s causing your issue.

OH 2.5:


Could you please check, if your Items show any links to channels.
Looking at your screenshots, seems that none of your old items got linked to the thing channels, instead new items had been created.

The thing channel seams linked to the item:

So far as I guess the item is not linked :