In the latest post to her blog Lorna Mitchell talks about some of the issues she had when upgrading to the latest version of SugarCRM (6.0.0).

I noticed that SugarCRM have just released their new version 6.0.0, and since my sugarcrm installation is madly out of date and I'm about to start using it again, I thought I'd just throw the old one away and install from scratch. I had no problems until I reached the final installation stage, when clicking the "install" button would return a 404.

After running through things a few times more, she finally corrected the cause of some of the errors of this final step - increasing the memory_limit setting, upload_file_size as well as installing cURL support for PHP. With these changes, the install worked perfectly.