CS4: the user encountered a 502 agent error when accessing FTP server using IE and did not pop up the enter user credentials dialog box

Summary of customer questions:

The user encountered a 502 agent error when accessing FTP server using IE. When the browser uses ftp://ftpServerName to access the self-test FTP server, the user does not prompt for user credentials to report error 502.

HTTP 502 Proxy Error-The login request was denied

Solution: through the understanding of the customer environment, we know that the customer uses TMG as the web agent for FTP access, and informs the customer that this error is a product design error. Such as the underlined part: when the client Web agent accesses an external FTP site, it should be accessed in ftp://username:password@FTPServerName format.

Further communication learned that the customer wants to use the dialog box to prompt for credentials for FTP access, reply to customers when using IE as the FTP client, and want to access FTP when they want to pop-up user credential input window

Enable folder view for FTP sites needs to be enabled on the client side IE, this option IE11 is enabled by default.