Citrix Profile Management: VHDX-based Outlook cache and Outlook search index on a user basis.

Behaviour prior to Profile Management 7.18

There have been two Outlook-related performance challenges with Citrix Profile Management.

To best explain, we’ll take a user that has an existing Profile Management 7.17 profile and launches published Outlook (or opens Outlook in a desktop session). Outlook has been configured to use the Outlook .OST cache. The location of the file is typically:

C:Users<user>AppDataLocalMicrosoftOutlook<email address>.OST

In Outlook cached mode, the OST file can be very large, so there is a significant overhead if the OST file is part of Profile Management logon/logoff synchronization.

Actions in Outlook, such as sending/receiving mail result in changes to the Outlook search index database. This data is stored in the Windows search index database: Windows.edb.

This is a machine-based file, which means it holds search index data for all users logging onto the machine. If a user launches an Outlook session (or opens Outlook in a desktop session) on a VDA machine that they haven’t access previously or haven’t accessed for a while, the Outlook search index has to be rebuilt in Windows.edb. Outlook searches have to wait until re-indexing finishes. The location of the Windows search index database is typically: C:ProgramDataMicrosoftSearchDataApplicationsWindowsWindows.edb

We can see this design in the image below:

User-added image

Behavior using VHDX-based Outlook cache and Outlook search index on a user basis

The Profile Management 7.18 release introduced a feature to address these Outlook-related performance challenges.

To explain we’ll use the same user as above, but logging on to a 7.18 version VDA for the first time.

During the Profile Management logon, the user’s Outlook-related search index is split out of the Windows search index database (Windows.edb) and written to a VHDX file created at:


The remote VHDX file is then mounted locally in the user’s local profile at:


From this point, the user has their own profile-based version of the Outlook search index database. Within the Search.vhdx mount-point folder, the Outlook search index database is named < userSID>.edb

The Outlook .OST file is converted into a VHDX file and stored at:

PathToUserStore<User_information>VHD<Platform> OutlookOST.vhdx

The remote VHDX file is then mounted locally in the user’s local profile at (default):


During the Outlook session, changes to the Outlook search index and Outlook .OST are made directly to their respective VHDX files over SMB.

The feature also requires additional registry settings to be created. Read the Registry Changes section for further information.

When the user logs off the session, both VHDX files are unmounted from the local profile. Because the VHDX files had been mounted over SMB, no synchronization is required at Profile Management logoff. The additional registry settings are synchronized to the user’s profile store (or before if the Active Writeback Registry feature has been enabled).

Feature Enhancements introduced in Citrix Virtual Apps and Desktops 1808

The Profile Management 1808 release Outlook search index feature supports groups explicitly excluded through the Profile Management Excluded Groups policy as well and groups implicitly excluded through the Profile Management Processed Groups policy (see Feature Limitations for further information).

This release also introduced support for Windows 10 1803.

Feature Limitations


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How to fix Event ID 455 ESENT error on Windows 10

ESENT is a built-in database search engine on your PC which helps File Explorer, Windows Search to search for parameters throughout your Windows 10 computer. If you’re encountering the Event ID 455 ESENT error on your Windows 10 device, then this post is intended to help you. In this post, we will provide the potential solutions you can try to mitigate this issue.

When this error occurs, you’ll see in the event log the following error description;

svchost (15692,R,98) TILEREPOSITORYS-1-5-18: Error -1023 (0xfffffc01) occurred while opening logfile


Fix Event ID 455 ESENT error

If you’re faced with this Event ID 455 ESENT error on your Windows 10 PC, you can try either of our two recommended solutions presented below to resolve the issue.

  1. Create Database folder in TileDataLayer folder via File Explorer
  2. Create Database folder in TileDataLayer folder via Command Prompt

Let’s take a look at the description of the process involved concerning either of the listed solutions.

1] Create a Database folder in TileDataLayer folder via File Explorer

To create a Database folder in TileDataLayer folder via File Explorer, do the following:

  • Press Windows key + R to invoke the Run dialog.
  • In the Run dialog, copy and paste the directory path (assuming the C drive is housing your Windows 10 installation) below and hit Enter.
  • Now, right-click on the open space and then click New >Folder to create a folder in that location.
  • Next, rename the new folder as TileDataLayer.
  • Now, double-click the newly created TileDataLayer folder on it to explore it.
  • Again right-click on the space within the open folder and then click New >Folder to create a new folder.
  • Rename the new folder as Database.
  • Exit File Explorer
  • Reboot your computer.

After rebooting the Event ID 455 ESENT error should be fixed.

Alternatively, to achieve the same result using File Explorer, you can use the CMD Prompt. Continue below to see how.

2] Create a Database folder in TileDataLayer folder via Command Prompt

To create a Database folder in TileDataLayer folder via Command Prompt, do the following:

  • Press Windows key + R to invoke the Run dialog.
  • In the Run dialog box, type cmd and then press CTRL + SHIFT + ENTER to open Command Prompt in admin/elevated mode.
  • In the command prompt window, copy and paste the syntax below one by one and hit Enter after each line to execute them sequentially on your computer.
cd configsystemprofileAppDataLocalmkdir TileDataLayercd TileDataLayermkdir Database
  • Once the task completes, exit the CMD prompt.
  • Reboot your computer.

After rebooting the Event ID 455 ESENT error should be fixed.


ESENT is an embeddable, transactional database engine. It first shipped with Microsoft Windows 2000 and has been available for developers to use since then. You can use ESENT for applications that need reliable, high-performance, low-overhead storage of structured or semi-structured data. The ESENT engine can help with data needs ranging from something as simple as a hash table that is too large to store in memory to something more complex such as an application with tables, columns, and indexes.

Active Directory, Windows Desktop Search, Windows Mail, Live Mesh, and Windows Update, currently rely on ESENT for data storage. And Microsoft Exchange stores all of its mailbox data (a large server typically has dozens of terabytes of data) using a slightly modified version of the ESENT code.


Significant technical features of ESENT include:

  • ACID transactions with savepoints, lazy commits, and robust crash recovery.
  • Snapshot isolation.
  • Record-level locking (multi-versioning provides non-blocking reads).
  • Highly concurrent database access.
  • Flexible meta-data (tens of thousands of columns, tables, and indexes are possible).
  • Indexing support for integer, floating-point, ASCII, Unicode, and binary columns.
  • Sophisticated index types, including conditional, tuple, and multi-valued.
  • Columns that can be up to 2GB with a maximum database size of 16TB.


  • No additional download needed. ManagedEsent uses the native esent.dll that already comes as part of every version of Microsoft Windows.
  • No administration required. ESENT automatically manages log files, database recovery, and even the database cache size.

Note: The ESENT database file cannot be shared between multiple processes simultaneously. ESENT works best for applications with simple, predefined queries; if you have an application with complex, ad-hoc queries, a storage solution that provides a query layer will work better for you.


How to Configure Files and Folders to be Available Offline on ShareFile Desktop App for Windows

You can make files and folders available offline. To make a file or folder available offline, right-click the item and choose the Make Available Offline option. When working offline, you can find the Offline Files section by clicking the navigation drop-down as shown below. Offline files have a green icon to the right of the file name.

User-added image

You may view and edit these files, but changes made to these documents will not be uploaded to ShareFile when a connection is reestablished. When accessing an offline file, you will be prompted to “download” the file to a location on your computer. When a file is made available offline, a copy of the file is stored and encrypted locally, then retrieved from that location when you “download” the file. The Desktop app is not communicating with the web application during this process.


Error – “Cannot start Microsoft Outlook. Cannot open the Outlook Window”

Disabled Windows Search Indexing for any outlook items.


1. To resolve this issue, add the following key to the Registry to prevent indexing of any Microsoft Outlook items


Data type: REG_DWORD

Key: SoftwareMicrosoftWindowswindows SearchPreferences

Value name: PreventIndexingOutlook

Value data in Hex: 0x00000001


Restart the Outlook client and Windows Desktop Search Service.


While Outlook is still running, open Control Panel, find Index Options and open it. Then click Modify button and uncheck Microsoft Outlook from the list and click OK.



Enable the below GPO to Prevent Indexing Microsoft Office Outlook.

Computer ConfigurationAdministrative TemplatesWindows ComponentsSearchPrevent Indexing Microsoft Office Outlook.​



Search Service fails to start, error 0x80071a91 / 6801

The search service fails to start or routinely crashes with errors that look like this:

Windows Search Service failed to process the list of included and excluded locations with the error <20,0x80071a91, “”>

The Windows Search Service has failed to create the new search index. Internal error <10,0x80071a91, Failed to save Crawl Scope Manager changes>

The Windows Search service terminated with the following error:

Transaction support within the specified resource manager is not started or was shut down due to an error.

You may also see a reference to error 6801. 80071a91 is “Transaction support within the specified resource manager is not started or was shut down due to an error.” These are all the same error.

The solution to fix this within an individual machine appears to be to run CMD as Administrator and do this:

cd C:WindowsSystem32ConfigTxR

attrib -r -s -h *

del *

If you identify this as a problem in an individual layer, you might be able to do the same there. Stop the Search Service (if present at all), delete the TxR files, and then finalize before allowing Search to start again.

If the TxR folder is not present, make sure you create one before starting the service again.


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How do I save the SQL history from the desktop nco_config client?

I have a large number of saved SQL queries in the nco_config desktop client. I use these queries all the time and love having the history. I have to upgrade to a new desktop and need to know how to move this to the new system. Is this possible?

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[1]: /answers/storage/temp/18006-screenshot544.jpg