Drupal 7, 8: Your Server Does Not Support Installing Modules & Themes

On my Windows 10 machine, I installed Drupal 7 and 8 on IIS Server. When I wanted to install modules, it gave the following error.

Error: Your server does not support installing modules and themes.

This issue is related to permission only.

Windows Configuration

  • Windows 10
  • IIS Express
  • PHP 7.1 (As FastCGI on IIS)
  • Application Pool Name: DefaultAppPool

Root Cause

IIS application runs under application pool permission. The default application pool name is “DefaultAppPool” but you may also create your own application pool with a specific name.

On IIS Server, Drupal is running under “DefaultAppPool” user. When we try to install module or theme, this user needs write permission to install module or theme. If “Write” permission for “DefaultAppPool” is missing on certain folders, Drupal will throw the above error.

Fix For Drupal 7 & 8

On the following folders, follow the steps to give application pool “Write” permission

  • DRUPAL_ROOT\sites\all
  • DRUPAL_ROOT\sites\default
  • C:\Windows\Temp (needed for PHP file upload and not related to Drupal)

For above folders, Right Click > Properties > Security tab > Edit > Add…

Type “IIS AppPool\YOUR_APPPOOL_NAME” for username. I am using DefaultAppPool so I entered “IIS AppPool\DefaultAppPool”. If you are using a different application pool name, use your own application pool name.

Click Check Names button and click OK.

Provide “Full Control” to these folders and click OK to all open dialogs.

Go back to Drupal and try to add Module/Theme.

Hopefully your error is gone.



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