Encountering a blank page or partially formatted page suggests that a fatal PHP error is occurring.
Please begin your troubleshooting by enabling the Setup > General Settings > Other tab > Display Errors option and then reproducing the blank page problem.
You should now see an error output to the screen. We have collected some of the most common errors and their causes, refer to the appropriate page in the following sections:
You can find more detailed instructions in our Troubleshooting Guide.