Importing old (5.1) designs into new(est) version of KiCad

[AlfEH]

I’ve been using KiCad a couple of years ago (both 4 and 5), and created a medium sized project with PCB layout, BOM files and all.
Quite some custom symbols and footprints used.

Now I need to make some changes to this project, and thought it would be wise to upgrade and use the latest version of KiCad.
But, when opening this project in e.g. KiCad v9, I get a lot of errors, symbols not found etc, and although I’ve been putting in some effort regarding library setup etc, I’m still seeing a lot of errors when e.g. opening the “Assign footprints” dialog.
The custom lib stuff is placed in separate .lib, .kicad_mod files, in a separate catalog.

I’ve read some of the (rather good) documentation, but cannot find much directly useful regarding compatibility and version conversion.

Is there a recommendation or guide to make this work, or do I need to stay with the 5.1 version?

Maybe export from 5.1 first, or maybe import the 5.1 into v9 and to include all lib & symbol stuff.
Cause I’d really like to avoid to redraw/recreate all the custom stuff…

BTW I’m running MacOS.

TIA
-Alf

[RaptorUK]

Start with the Manual, there is a section in there about “upgrading” from earlier versions . . .

KiCad | 9.0 | English | Documentation | KiCad

[AlfEH]

Thank you for your swift and spot on answer!
I’ve read the section you point at, and also been able to import the most relevant parts of our custom library and symbols, so now I’m happy with continuing with v9 of KiCad!

Thank you!