From the stack trace, it looks like the system cannot find the backend login page with the passed it. Does the issue persist after you recycle the application pool, also, are you able to reproduce the issue on a local machine? The stack trace does not have any code from the dynamic modules, that is why it is difficult to determine what exactly caused the issue.
In order to resolve this as quickly as possible, please, contact the license holder in order to be added as a licensed developer. Once this is done, you will be able to open a support ticket and we will be able to provide you with a FTP for the project and database. After we have the file, we will be able to debug the issue and provide a solution as soon as possible.
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