Upgraded a SugarCRM 6.5.16 to 7.1.1 a while back and have been running it successfully with no issues. When upgrading to 7.1.2 it works, but when I save changes to any record (at least in the cases which I spend much of my time in) I get a white blank page. Saw one post saying that the field names may not have changed and I did see some errors in the log, but adjusting this did not help.
Upgrading from 7.1.1 to 7.1.2 results in issues when updating records
Have you tried doing a quick repair and rebuild? Check your file permissions also.