Might be mistaken but I don't think importing/exporting between versions is supported. Sure a CMS 6 R2 will probably take a CMS 6 R1 import file, but not between major versions.

http://world.episerver.com/Documentation/Items/Tech-Notes/EPiServer-CMS-5/EPiServer-CMS-5-SP1/Migrating-from-CMS-462-to-CMS-5-SP1/#Using%20export/import

That one states that 4.62 files works for CMS 5 SP1. I heard that someone had successfully used a 4.62 file for CMS 6 R2 as well.

But maybe 7 is too altered for any older export package to work...

I successfully imported a 4.61 package into CMS 6 R2 today. 

CMS7 does not support *.epif4 files, that was handled in EPiServer.Legacy4 assembly which is not compatible with CMS 7.

However .episerverdata packages from for example CMS6R2 should work fine to import to CMS7. So a workaround for you if you need to get data from a 4 site to 7 is to have cms6 as an intermediate site/state.

OK, thanks for the info!

Is there somewhere where I can read about how to import a 4.61 package into CMS 6 R2? Or can you perhaps explain in more detail of how to do it?

@JS:

Use Import/Export to migrate to a newer version if you're mainly interested in migrating the content. Be aware that this method won't migrate your VPP/file archive (only files that are referenced in content - and sometimes they aren't even migrated correctly).
Export packages from 4.61 can be imported into both CMS 5 and CMS 6 (but not CMS 7, as mentioned above).

TIP: If you want to look inside an .epi4 file to see or modify contents, use this tool. 

Importing 4.61 data to CMS 6 R2 requires you to have the same pagetypes, tabs and categories on the target site as the source site.

In 4.61, go to Admin > Export data and select the following:

• Pages (select start node to export from, check "Export files" and "Export globalized pages")
• Page types (select all the page types your content uses, skip SysRoot and SysRecycleBin)
• Dynamic Property Definitions (if you have any)
• Tabs (check all)
• Categories (if you have any. I don't think your import will fail if you skip this though)
• Files (I would skip this - you can only select files one by one, you should find another way to migrate your file archive)

NOTE: If you choose to export everything at once, you should end up with a .epi4 file.
But actually, I would make a separate export of each of the bullet points above (pages.epi4, pagetypes.epi4, etc), so you have better control over what's imported later. Then import them in CMS 6 R2 in the following order: Categories, Tabs, Dynamic Properties, PageTypes, Pages.

In CMS 6 R2, go to Admin > Import data and point to your .epi4 files ("Select page destination" is only applicable when you're importing Pages).

TIP: Use the "Upload and verify" button first to see if the importer finds any problems.

Very useful, thanks! So I don't need to install anything other than the CMS 6? Someone mentioned a legacy dll?

Is it only 4.61 and upwards that works to export and import? No other versions of EPiServer 4 supported? I'm currently working with 4.51

@JS: The EPiServer.Legacy4.dll file that Johan mentions above is shipped with CMS 5 and 6 (in your bin folder) to give support for some legacy functions from EPi 4. You don't have to add anything.

I am not sure if the export package from 4.51 will work (only tried 4.61) - you'll just have to test yourself.

Also please note that you can't export forms (XForms) using the built-in export/import tool.