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FSLogix - How It Works - What Can Go Wrong - How To Troubleshoot

FSLogix has been challenging for many people, especially now in the early days of AVD. Our article here explains what FSLogix is doing in a general sense, and is a recommended first read.

The article below walks you through a brief overview of FSLogix in Nerdio for Azure (NFA), a few things that could commonly go wrong, and finally how to troubleshoot those issues.

How it works

The understanding of the orchestration of FSlogix with profiles will make logical sense when you look at the pieces and parts that FSLogix puts together.

  • FSLogix services are part of every deployment done with Nerdio for Azure (NFA) or Nerdio Manager for MSP (NMM)
  • In NFA,
    • Registry entries are configured to enable FSLogix and point the profile storage to  \\FS01\Profiles\%username%
    • There is another registry entry that excludes DESKTOP, DOCUMENTS and FAVORITES folders from FSLogix profile because those are redirected to \\FS01\USERS\%username% folder. This registry entry points at an XML file that tells FSLogix to exclude those folders. This file is \\FS01\Profiles\redirections.xml
  • In NMM,
    • Users profiles are stored at a UNC path of your choosing, or in Azure files.
    • Additional FSLogix configuration is up to you.

What can go wrong?

We’ve seen a number of situations that can cause FSLogix profile redirection to not work.  Here is a list of the most common ones. (And you can find their fixes in the section below: "Fixes for each issue" )

  1.  User profile location cannot be accessed by the user who is logging in because of permissions issues.
  2. User profile location cannot be accessed because of DNS issues as a result of Hybrid AD being enabled and users not being able to resolve FS01 (needing to resolve instead)
  3. An existing local profile prevents FSLogix from creating a new profile and the user continues logging in with the local profile
  4. Profile VHD file is locked by another user session.  This can often happen when a user has a disconnected session on another session host that keeps the profile file locked but AVD connection broker places the user on another host and is unable to map the profile.

How To Troubleshoot?

  1. There is no “local_%username%” folder in C:\users while the user is logged in. This means FSLogix isn’t working.
  2. The date/time on the VHD file in User profile location is not current. This means FSLogix isn’t mapping properly and changes aren’t being saved.
  3. Event Viewer FSLogix Operations log is showing errors. Each error has a code, if you search FSLogix codes you’ll be able to identify what the root cause is.
  4. Additional information is available in the logs. Find these in the pool host that serviced the users login attempt. Like \\Pool-A00000N\c$\ProgramData\FSLogix\Logs\Profile\
  5. Login to FS01 and check permissions on the user's VHD file in User Profile Location\%Username%\Profile_%Username%.vhdx and right click to check security permissions
  6. For NMM, See additional troubleshooting for NMM specifically, here.

Fixes For Each Issue

  1.  This is a permissions issue and the permissions should be set back to the default.
  2.  Update the registry entries on the pool template to point at \\ (or whatever the Nerdio AD FQDN is). There are two registry entries to change. Set template as image and update existing hosts.
  3. Remove the local profiles from the session host and/or template VM. Alternatively, implement the “delete local profile when it exists” registry entry on the template so FSLogix does that automatically.
  4.  Find the other session on another host, log it off. It’s important to do this rather than just killing the file handle since there may be a RW VHD file that needs to be merged with the main profile. If the file handle is closed without logging off, then the RW file will be discarded and some changes that user made may be lost.
  5. Change the configuration on the global AVDSH00 template to not exclude Domain Admins from mapping FSLogix. 

Recreating A User Profile

There are times where it may be necessary to recreate a user's profile. Assuming the default folder redirections are in place, recreating the profile will not delete the user's Desktop, Documents, or Favorites folders. Note that any files saved elsewhere in the profile and any profile customizations will be lost. You can use the following steps to recreate the profile:

  1. On FS01, go to E:\Profiles and navigate to the user profile you are trying to recreate. The full path to the profile container will be E:\Profiles\%Username%\GUID_username\Profile_%Username%.vhdx.
  2. Once you have located the profile container, you can either delete it or move it to another location if you are unsure if deleting would pose risk of data loss. The user must be logged off and the container unmounted in order to perform this step.
  3. Have the user log into their desktop. A new profile container will be created.


Final Note

From time to time in NFA, the FSLogix application on the Pool hosts or Personal desktops will need to be updated/upgraded.  The context of the application in AVD and it's download of the FSLogix applications can be found at:


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Important Notification for NFA Partners Only
  • Microsoft is sunsetting Azure Classic (not Azure Virtual Desktop (AVD)) - Microsoft Article
  • NFA sunset occurs February 20th, 2023
  • NFA will be fully supported until the official sunset -


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