I needed to change my web.config file to development in a medium-trust environment, because that is what my hosting provider allows. I added this line in the configuration\system.web element:
After trying to view my application, I immediately received this error:
Server Error in ‘/’ Application.
Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.
Parser Error Message: Unable to read the security policy file for trust level ‘medium’.
Porque? Because the web.config file is case-sensitive. This simple change made the application work again: