Thank you for your forum post and sorry that you have encountered a problem.
A support call has been created for you, the call reference number is F0069729.
Can you please send an e-mail to email@example.com
with the above call reference number in the subject field.
In the e-mail can you please confirm the following:
1. License serial number (if you have purchased the product)?
2. Exact version of SQL Data Compare you are using?
3. Information regarding each data source you have selected, if it is a live database what is the SQL version in use?
4. Does this error occur for other databases?
Also can you change the SQL Data Compare logging level to verbose, repeat the process and when the error occurs, copy the log file and attach it to your e-mail reply?
To change the logging, right click the SQL Data Compare icon immediately above the file menu option in the top left hand corner of the GUI. Set the logging to verbose. To obtain the log file, repeat the steps to set the logging level but select the option for the log file.