IIS 7 and Above
The Module DLL C:\Windows\system32\inetsrv\rewrite.dll failed to load...
Last post Nov 29, 2010 11:51 PM by Lloydz
Nov 25, 2010 03:32 PM|jestwest|LINK
Nov 29, 2010 11:51 PM|Lloydz|LINK
Would you please check if “rewrite.dll” exists in the folder "C:\Windows\System32\inetsrv"? If the dll doesn't exist, you need to download a correct URL Rewrite Module version and install it.
Please also check the following article to get more information about troubleshooting 503 error:
Where did my IIS7 server go? Troubleshooting 503 "service unavailable" errors
Hope this information helpful for you ,thanks.