Article ID: 125161, created on Apr 8, 2015, last review on Apr 8, 2015

  • Applies to:
  • Plesk 12.0 for Windows
  • Plesk 10.4 for Windows


Password-protected directory is not allowing access, regardless of the fact that valid credentials are used. IIS error 401 appears:

    Access is denied due to invalid credentials


Additional/custom ISAPI filter is enabled on domain that prevents password protection work.


  1. Go to:

    IIS manager > host > Sites > domain.tld > ISAPI Filters

    And make sure ISAPI filter 'url_protect' is present:

    C:\Program Files (x86)\Parallels\Plesk\isapi\urlprotect.dll 

    All other url protect filters must be custom ISAPI filters.

  2. If you see any additional .dll ISAPI filters for url protect, such as:


Please remove them and check directory protection once again.

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