We are planning on upgrading our backup infrastructure from Symantec Backup Exec 2010 – R3 to the Backup Exec20. If we go with Backup Exec 20, will I be able to migrate all my catalogs from Backup Exec 2010 into Backup Exec 20?
Your catalogs will be converted as part of the upgrade process. In your case, you have to upgrade to an intermediate release before upgrading to BE 20. Check the BE 20 SCL to see which intermediate release you need to upgrade to.
Also check the BE 20 SCL to see whether support for your software has been dropped, e.g. Lotus Domino.
Please see this TN: https://www.veritas.com/content/support/en_US/article.100018032.html
There is a table that shows supported upgrade paths.
You need to be on BE2010 R3, SP4 in order to upgrade to BE15 or 16.
You can then upgrade to 20.x.
The doc also contains step-by-step instructions.