Outlook 2007: You are unexpectedly prompted to upgrade your .ost file to Unicode mode when you start Outlook

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When you start Outlook you may receive the following prompt:

The Offline Folder file C:\Documents and Settings\<username>\Local  Settings\Application Data\Microsoft\Outlook\<filename>.ost cannot be used in this profile. Your administrator has set a policy that allows you to use only those Offline Folder files that provide greater storage capacity and support multilingual Unicode data.

When you click OK the Offline Folder File Settings dialog box appears and you are prompted to specify a location for your .ost file.

This is unexpected because you have already deployed the following group policy settings to force the upgrade of your profile from using an ANSI .ost file to using a Unicode .ost file.

Exchange Unicode ModeSettings

Exchange Unicode Mode - Prefer ANSI

Do not prefer ANSI mode

Exchange Unicode Mode - Ignore Archive Format

Ignore existing format of the Archive PST

Exchange Unicode Mode - Ignore OST Format

Create new OST if format does not match mode

This problem occurs because the Outlk12.adm group policy template does not include the policy setting to silently upgrade your profile to use a Unicode .ost file (from the previously configured ANSI .ost file)

To resolve this problem you can either deploy the registry data that performs this silent profile upgrade process or you can create a custom group policy template file.

NOTE: The upgrade process does not upgrade an ANSI .ost file to a Unicode .ost file. This process simply creates a new Unicode .ost file for your profile, leaving the original ANSI .ost file alone.

  • Deploy registry data to perform a silent profile upgrade to a Unicode .ost file

To suppress the prompt to upgrade the .ost file, deploy the following additional registry data on your workstations with Outlook 2007.

KEY: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Outlook\EMSP
DWORD: SilentOSTFormatChange
VALUES: 1 = perform silent upgrade, 0 = do not perform silent upgrade

  • Create a custom group policy template file.

If you prefer to push out this change using group policy, please use the following steps to create a custom group policy template file (.adm).

1. Open a new text file using Notepad.
2. Add (copy/paste) the following lines of text into the file.

;// _lcid="1033" _version="12.0.6425"
CATEGORY !!L_MicrosoftOfficeOutlook12SilentOSTFormat
CATEGORY !!L_ToolsAccounts
CATEGORY !!L_Exchangesettings
POLICY !!L_ExchangeUnicodeSilenteOSTFormatChange
KEYNAME Software\Policies\Microsoft\Office\12.0\Outlook\EMSP
 VALUENAME SilentOSTFormatChange
 EXPLAIN !!L_Choosewhethertheostformatchangeissilent
L_MicrosoftOfficeOutlook12SilentOSTFormat="Outlook 2007 Silent OST format change policy"
L_ToolsAccounts="Tools | Account Settings"
L_ExchangeUnicodeSilenteOSTFormatChange="Silent OST upgrade"
L_Choosewhethertheostformatchangeissilent="Perform silent .ost file upgrade from ANSI mode to Unicode mode"

NOTE: Make sure the text for lines beginning with “L_” do not wrap onto multiple lines. Each line should appear as one single line of text in the .adm file. Please turn off Word Wrap on the Format menu to confirm the text is on a single line.

3. Save and close the file as Outlk12-SilentOSTFormatChange.adm.
4. Add the Outlk12-SilentOSTFormatChange.adm file to the group policy editor.
5. Expand the group policy tree to the following node:

User Configuration\Administrative Templates\Outlook 2007 Silent OST format change Policy\Tools|Account Settings\Exchange

6. Double-click the Silent OST upgrade policy.
7. Select Enabled and click OK.



Article ID: 2000633 - Last Review: 12/12/2015 04:53:07 - Revision: 4.0

Microsoft Office Outlook 2007

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