This usually an indication that you have a corrupt job type and/or workflow in the your existing repository. At 10, the job type and the workflow are stored in separate tables. So we have to extract your workflow from your job type and import the workflow XML into the workflow table.
I think this is where it is failing.
Did you have a job type that was causing issues (throwing errors) prior to your upgrade? You can try to create different jobs from every job type you have in your repository and view the workflow for these jobs in the application. This might help narrow down the issue better.
I hope this helps!