RE: Vendor Maintenance window not open in GP 2013 Web Client
I'm guessing that you have Project Accounting installed on your Dynamics GP system. Project Accounting uses alternate versions of the Customer Maintenance and Vendor Maintenance windows. In the web client, all of the Project Accounting resources are being prevented from opening. Because security is set to use the alternate versions of the Customer Maintenance and Vendor Maintenance windows, but PA isn't accessible, these windows aren't accessible. :-(
One possible solution is to revise the security to use the original versions of these two window, rather than the alternate versions provided by Project Accounting.
A more complex solution would be to figure out which records from the "knock out" table need to be removed to allow the alternate versions of the forms to be opened. This solution also assumes that the alternate versions don't have any issues in the web client.