.net – Unable to use 80 as a HTTPS port in IIS6 when .NET Framework 3.5 is installed

.net-3.5iis-6

After upgrading to .NET Framework 3.5, I can't set 80 as a HTTPS port in IIS6.
Only when I uninstalled .NET Framework 3.5, IIS accepts 80 as a HTTPS port again and operate normally.

The question is whether this behaviour is by design or a bug results from unexpected interaction between IIS and .NET Framework 3.5.

To my understanding, Dot Net Framework should be web server agnostic and IIS should be software framework agnostic. Thus, if this behavior is indeed a design choice, why it did not show up in early versions of Dot Net Framework, e,g. 1.1 2.0？

Reproduction Steps：
1. Set 80 as a HTTPS port in IIS6

  1. Install .Net framework 3.5

  2. run "inetmgr", it appears that website is stopped.

  3. Remove port 80 from https configuration or uninstall framework 3.5, website is able to start again

Best Answer

I just ran into the same issue trying to load a piece of software what uses port 80. For me, it was in the Web Server (IIS). .Net required certain services installed with the Web Server (IIS) and automatically starts those services. If you go to...

Server Manager, Roles, Web Server (IIS), System services.....Then, Stop the "World Wide Web Publishing Service"....Then, you should be able to use port 80.

Make sure that if you don't want that services to start back up when you restart the server, to set the "Startup Type" to "Manual"

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