Windows Process Activation Service Error 2:The system cannot find the file specified - asp.net

Question

IIS on my development computer stopped working. I just installed the latest update to windows 10 (1803) and now when I try to start the "Windows Process Activation Service" I get an "Windows could not start the Windows Process Activation Service on Local computer. Error 2: The System cannot find the file specified" error. Things I have already tried:
Reinstalled IIS and Windows Process Activation Service, several times
I verified that I do have a "C:\inetpub\temp\appPools" folder
Not sure what to do next.

Answer 1

I have had this problem twice after a windows update. The issue seems to be, that windows adds an incorrect parameter to the WAS service startup parameters. I fixed the issue using the following steps:
Start regedit (just type it into start)
Navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WAS\Parameters
Delete the NanoSetup variable. This variable is preventing WAS from starting
Start the WAS service using task manager or by typing "net start WAS" in Command Prompt
Start the W3SVC service the same way
You can now start your website in IIS again

Answer 2

I had the same problem and nothing in here was the solution for me for a long time. So i rolled back windows also. Today i found the solution working for me - Navigate to:
C:\Users\All Users\Application Data\Microsoft\Crypto\RSA\MachineKeys\
find these 3 Key-files...
d6d986f09a1ee04e24c949879fdb506c_*
76944fb33636aeddb9590521c2e8815a_*
6de9cb26d2b98c01ec4e9e8b34824aa2_*
... then in Security-Settings:
first, you have to set your User as OWNER
close Properties Dialog - and open again
Then in ACL set "full controll" for SYSTEM
After that: WPA can be started...
Hope this helps; see also thread here: https://social.technet.microsoft.com/Forums/en-US/315841e1-b8b2-4084-8224-580ef3d13420/upgrade-to-windows-10-1709-iis-fails?forum=win10itprosetup

Answer 3

I had this same problem after installing the Windows 10 1909 update and the nanosetup variable was NOT in the registry. I ended up doing a variation of Sascha's fix.
I took ownership and gave administrators full control of the MachineKeys folder in C:\ProgramData\Microsoft\Crypto\RSA. Then I removed the 3 files in Machinekeys that begin with:
d6d986f09a1ee04e24c949879fdb506c_*
76944fb33636aeddb9590521c2e8815a_*
6de9cb26d2b98c01ec4e9e8b34824aa2_*
The Windows Process Activation Service (WAS) started as expected.

Answer 4

It just has a simple solution, you don't need to reinstall Windows or removing updates, It worked for me so sharing it with all of you,
if you already using IIS and have site's configurations and files in C:\windows\system32\inetsrv\config and C:\inetpub\wwwroot, Back up all files from the folder C:\windows\system32\inetsrv\config and C:\inetpub\wwwroot, if you are installing ISS for the first time then you don't need to have a back up.
On Taskbar right-click on Start button select 'Run', type appwiz.cpl hit Enter.Click on 'Turn Windows features on or off'.
Uncheck 'Internet Information Services' and 'Windows Process Activation Service' click OK button.
After restarting Windows, Delete 'inetpub' folder on C: drive.
Open 'Turn Windows features on or off window' again.
Check 'Internet Information Services' and 'Windows Process Activation Service' click OK button.
After restarting Windows open folder C:\windows\system32\inetsrv\config.
Right click on the file named 'applicationHost' Select Open with Notepad.
In Notepad, Copy all the content of the file.
Select New in File Menu and Paste all the content in the new file.
Save this file in C:\windows\system32\inetsrv\config with the name 'applicationHost.config.tmp', Don't forget choosing 'All Files' in the 'Save as type' box.
Otherwise, file will be saved as applicationHost.config.tmp.txt which will not work.
Type 'Services.msc' in Run, Find 'Windows Process Activation Service' in Services window.
Watch running the service successfully without any errors after clicking on start.

Answer 5

I finally had to give up and rollback the windows build. To do this follow these steps:
Go to settings (Windows+I)
Click on "Update & Security"
On the left click on "Recovery"
Then under "Go back to the previous version of Windows 10" click "Get
started"
It rolled back to "1709" and now works fine.

Answer 6

If you find yourself installing an application on a drive other than C: and that application relies on IIS, the path for inetpub temporary files may be missing. Even if they are present on C:, this may just confuse you into thinking they are present and thus not the issue.
Create the following empty directory structure, replacing G: with the drive letter that your application is installed to, other than C:.
G:\inetpub\temp\apppools
Then, start WAS, from an administrator command prompt:
net start WAS
If this has to do with IIS, restart for good measure, from the same prompt:
IISRESET /restart
This solved my problem when installing a third party application.

Answer 7

I received the same error after update, but on Windows Server 2022 Standard 21h2.
Tried all steps without success.
In my case WU deleted all params in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WAS\Parameters
so i took it from old ControlSet002:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WAS\Parameters]
"AccessDeniedMessage"="Error: Access is Denied."
"InstallPath"=hex(2):25,00,77,00,69,00,6e,00,64,00,69,00,72,00,25,00,5c,00,73,\
00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,69,00,6e,00,65,00,74,00,\
73,00,72,00,76,00,00,00
"MajorVersion"=dword:0000000a
"MinorVersion"=dword:00000000
"ServiceDll"=hex(2):25,00,77,00,69,00,6e,00,64,00,69,00,72,00,25,00,5c,00,73,\
00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,69,00,6e,00,65,00,74,00,\
73,00,72,00,76,00,5c,00,69,00,69,00,73,00,77,00,33,00,61,00,64,00,6d,00,2e,\
00,64,00,6c,00,6c,00,00,00
"GenerateKeys"=dword:00000001
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WAS\Parameters\ListenerAdapters]