Installing and upgrading help

Can you use an earlier backup?

Alternatively, updates are happening almost every day for v2.0, each one is supposed to make it more stable, but sometimes someone forgets something.

AFAIK there are differences between the databases, but I do not think they would be so great as to not being able to repopulate a 1.9.8 database.

As a suggestion, if you have time, recreate the v1.9.8 do a backup of both and compare the structure. If there are large scale differences, they will show up immediately. I know there are over 200 tables but one table at a time may be the only option as far as repopulating the earlier db...

Or, you could go to the Developers forum and ask if there is a backward compatible SQL statement available that would allow to to do it...