Issue:

While importing a solution I got a generic SQL error but when i downloaded the log file i saw below error:

0x80044150 – Object reference not set to an instance of an object 

I have seen this error in plugins several times but never in import but root cause and underlying issue remains the same.

The import was trying to find something which was not there in target.

Solution

There was a relationship in my solution exist as N:1 to an entity which was deleted from target system way back hence this error occurred. Using the relationship given in solution, CRM was trying to find related entity which wasn’t there.

Hope this helps.