I have Drupal 8.4 running on Windows Server 2016, and when trying to use an upload field on a content type I get this error

The file phpC128.tmp could not be saved. An unknown error has occurred.
File upload error. Could not move uploaded file.

I deleted the files folder and the account PHP is running under, recreated it for this month as expected, but this still errors out. I see the file in c:\windows\temp, but it doesn't make it to my site folder. The account has full control to the files and 2018-06 folders.

In IIS, the AppPool is running under ApplicationPoolIdentity as well.

  • 1
    That error usually suggests the server can't write to the target folder - to debug, add a tiny standalone vanilla PHP file to the project which writes a file to the public files folder. If that works fine, you know the problem is somewhere in Drupal, otherwise it's folder permissions or some other environmental factor
    – Clive
    Commented Jun 30, 2018 at 18:58
  • a basic copy into that folder works, now what? Commented Jun 30, 2018 at 21:46

1 Answer 1


Moving the file path from `c:\windows\temp' to another location, and after setting the IUSR permissions on that new folder, it worked as expected!

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