It seems the dnn team is taking a well deserved weekend off, replies come slower than usual. I am not an expert, but having gone through the upgrades myself, I may give you a few suggestions that could help you solve the problem.

First of all, you will have to restore your version 4.9. I hope you made backups of your database and file system before starting the backup.

If your old version of DNN is below 4.9.5, then you should first perform an upgrade to 4.9.5. Check the new version thoroughly for issues.

Next, upgrade to version 5.4.4. Make sure that you have the .Net Framework 3.5 SP1 and that you are using SQL server 2003 or above and that you do not have compatibility mode set for SQL 2000.

You will have to update a few modules, the html module for one, and I think the Forum module.

From 5.4.4, you could move to 5.5.0 and then to 5.6.0, but if you have no compelling reason to do so, I would suggest to wait for the release of 5.6.1 (it is expected to be released soon now). DNN 5.5 and 5.6 implement content localization, but there are still some issues that 5.6.1 might solve. Content localization is an important new element in DNN, but they haven't got it quite right yet.

If you want to implement it in production, wait after the release of 5.6.1 and check the forums for issues that might come up.

---

____________________________________
The one-eyed in the land of the blind.