This has been an enormous problem for me recently as well.

The issue in my case:  if a Premium to Premium migration fails, then it frequently ( always? ) leaves your new Sage 100 version in a state where you can't get in, and the primary advice from Sage is to reinstall Sage 100 completely.

Reinstalling isn't a great solution since larger companies frequently have multiple enhancements that must be reinstalled.

In my case, I keep getting all sorts of errors - some of which seemed to be operating system related. And like Cullen - I'm going through an initial migration and a test re-migration to try and rule out problems on go-live day. It sounds like this is a common issue.

The only way I've found to combat this: 

1. Completely backup \MAS90 and all subfolders

2. Make a SQL backup of working MAS_SYSTEM and MAS_XXX databases

3. Save these for use if the migration crashes and results in one of several errors in which Sage offers no recovery option and only suggests a total re-install

I also try to clean up any prior MAS_xxx.BAK or MAS_SYSTEM.bak leftover from prior failed migrations

This is hugely frustrating and I think in the future will be a reason why Premium customers might upgrade infrequently

This has been an enormous problem for me recently as well.

The issue in my case:  if a Premium to Premium migration fails, then it frequently ( always? ) leaves your new Sage 100 version in a state where you can't get in, and the primary advice from Sage is to reinstall Sage 100 completely.

Reinstalling isn't a great solution since larger companies frequently have multiple enhancements that must be reinstalled.

In my case, I keep getting all sorts of errors - some of which seemed to be operating system related. And like Cullen - I'm going through an initial migration and a test re-migration to try and rule out problems on go-live day. It sounds like this is a common issue.

The only way I've found to combat this: 

1. Completely backup \MAS90 and all subfolders

2. Make a SQL backup of working MAS_SYSTEM and MAS_XXX databases

3. Save these for use if the migration crashes and results in one of several errors in which Sage offers no recovery option and only suggests a total re-install

I also try to clean up any prior MAS_xxx.BAK or MAS_SYSTEM.bak leftover from prior failed migrations

This is hugely frustrating and I think in the future will be a reason why Premium customers might upgrade infrequently

For the target system, a backup of MAS90 and MAS_System is enough to reset after a failed migration attempt.  I have done that many times.

Thankfully that's what I had last night. So far, I haven't seen any specific pattern to the errors. Most of mine don't seem to be the same error, but they frequently deal with rights or file-in-use problems.

To get back on my feet:

I renamed the \MAS90\... to old.MAS90\..

Copied back the backup copy of  \MAS90 (and all subfolders ) that I had saved

Restored MAS_SYSTEM SQL backup

Restarted migration 

The first time I did not have a copy of \MAS90 or MAS_SYSTEM, and a complete reinstall wasn't the way I planned to spend my night

I've been burned by that myself, and am now in the habit of taking a backup immediately after the initial software install (including enhancements and service config), so I can always reset to that point.

If you've done a test migration, and made changes to system settings (Roles...), take a fresh backup before trying another migration.  I've had initial test migrations go fine, only to have 2nd migrations fail with various errors.