Installing .Net 4.5 on IIS7.0 or IIS7.5 Server 2008 or Windows 7

Posted: 2012-11-19 in .Net

Its actually quiet simple (steps below) but be warned.


.Net 4.5 is a REPLACEMENT to 4.0, so after you install 4.5 there is almost no way in knowing that you have done so.
Even worse a 4.5 compiled website will run on a server with only 4.0 until it hits the 4.5 specific code (aka async or 4.5 dll).

The only best protection you can apply is in your web.config add a pre-check which results in YSOD (vs runtime error).

        <compilation debug="true" strict="false" explicit="true" targetFramework="4.5" />
Installing 4.5 In 4.5 easy steps

Step 1.

Go to Microsoft Download page and grab the 4.5 web installer (here)

Step 2

Run the web installer, get coffee and socialize for 15 minutes (3.0GHz dual core with no Anti Virus).

Step 3

Run the Microsoft Updates and get the latest patches (their was already 4 when I did this the first time)

Step 4



Step 4.5 Verifying The Results

In IIS if you check the application pool you get the….

Ok so no 4.5 so if you check the ISAPIR settings for IIS you get….

Ok again no 4.5. So is it installed? well yes but as stated in the first paragraph its an replacement (like 3.0 and 3.5 in IIS)

You can sort of check:
During Step 3 you get the 4.5 patches which is the first  indication that the install worked.


If you check in folder

you will now have 36 files (versus 29 before) as well as  support for the AeroLite theme (PresentationFramework.AeroLite.dll in the wpf folder).

The only upgrade issue we have had so far is that the 3.5 Workflow foundation refused to work when 4.5 was installed (weird).



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