Reinstall rewrite module. If you don't see this module in IIS and installed application list but rewrite installer says thar is is already installed go to registry (HKLM/SOFTWARE/MICROSOFT/WINDOWS/CURRENTVERSION/Uninstall) and serach 'rewrite'. Find uninstall string and run it. It will remove rewrite module and you can install from scratch.
Install Application Request Routing module for IIS.
IMPORTANT! If you already have web.config with rules remove them. Create/add rules via IIS menu. This way IIS will activate ARP module that is important.
Hope this resolves your Query !!
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