Some of the challenges that were reported included:
- Errors such as: Warning: Invalid argument supplied for foreach() in /home/xxxxx/public_html/xxxx/data/SugarBean.php on line 2322
- Inability to click Browse button to select upgrade files or Browse button missing
- Errors when clicking Upgrade Wizard link that prevent upgrade wizard from displaying altogether
The common thread between all of these issues is that SugarCRM in part relies on files stored in the /cache/upload directory in order for the feature to work correctly. Temporarily renaming the /cache folder prior to attempting to access the Upgrade Wizard feature appears to correct the problem.
It is strongly advised that one NOT delete the existing /cache directory as an alternate solution. The danger in doing so is that the /cache/upload directory is used to store e-mail attachments, documents and other files related to Sugar. Deleting that directory would in turn cause those files to be lost. DO NOT DELETE the directory.
Once you have successfully upgraded -- assuming the rename trick solves the problem -- the current /cache/upload directory contents will need to be merged with the contents of the /upload directory that resides in the renamed /cache directory.