GWSMO release notes

Use these release notes to review improvements and new features in each version of Google Workspace Sync for Microsoft Outlook (GWSMO).

For details about the current list of known issues, go to Google Workspace Known Issues.

We recommend that you upgrade your version of GWSMO to In the near future, older versions of GWSMO won't be able to reauthorize.

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Release notes for

June 18, 2024

What's new
  • GWSMO now uses the latest, most secure, version of the installer. If you have an issue installing the previous version, try installing this version.

Release notes for

March 31, 2022

What's new
  • Best security practices implemented to help keep your account and data safe.

Release notes for

November 30, 2020

What's new
  • G Suite Sync for Microsoft Outlook (GSSMO) is now Google Workspace Sync for Microsoft Outlook (GWSMO).
  • Now you can turn synchronization on or off for a specific product. For details, go to Turn sync on or off.

Release notes for

October 27, 2020

What's fixed
  • Fixed an issue that caused unexpected "Updated event" email notifications sent by Google Calendar when a meeting was accepted in Outlook.
  • Fixed an issue that caused color information for events in Google Calendar to be lost when the event was updated from Outlook.

Release notes for

October 5, 2020

What's fixed
  • Fixed an issue that prevented email being sent from a secondary IMAP account after a message was moved to the Outbox folder.

Release notes for

August 19, 2020

What's fixed
  • Fixed an issue that caused GSSMO to reuse the same RFC-822 message ID when sending a message that was copied from a previously-sent message. This caused messages to be treated as duplicates even when they're not.
  • Fixed an issue that caused GSSMO to reset the "See guest list" option in Google Calendar events.

Release notes for

June 29, 2020

What's new
  • Improved detection of conflicting add-ins. If you allowed anonymous usage statistics reporting when you created your G Suite Sync profile, GSSMO now also sends info about the presence of certain conflicting add-ins.
  • New G Suite Sync profiles default to RTF format for calendar events descriptions.
What's fixed
  • Fixed Sync Issues messages about Calendar events descriptions format being discarded due to unsupported HTML. GSSMO now sets the default editor format to RTF in new G Suite Sync profiles. Users upgrading GSSMO can work around the issue by following the instructions in Don’t save a calendar event with HTML format
  • GSSMO now points to the correct Sync Issues subfolder when you click the See details link in some error messages in the Sync dialog.
  • Fixed an issue where messages sent to an invalid (non RFC-5321-compliant) email address were silently discarded. GSSMO now posts an auto-generated non-delivery response message.
  • Fixed an issue that prevented GSSMO from placing its status icon on the Windows tray.
  • Updated time zone mappings for Metlakatla and Qyzylorda.
  • Improved tracing to help diagnose synchronization problems.

Release notes for

January 7, 2020

What's new
  • Improved detection of unsupported versions of Microsoft Office. If the installer detects an unsupported version of Office, it displays a clearer message with instructions to follow.
  • GSSMO detects if add-ins that are known to cause problems are used in conjunction with GSSMO. If the add-ins are detected, the user gets an Inbox message with instructions to disable the add-ins.
  • Improved reporting of anonymous internal statistics which help Google to diagnose common issues earlier.

    Important: Anonymous usage statistics are sent to Google if you check the Send crash reports and usage statistics to Google option when you create your G Suite Sync profile.

  • New OAuth endpoint used for exchanging authorization and access tokens. If you have a firewall, make sure the new endpoint is whitelisted:
    • Old endpoint:
    • New endpoint:
What's fixed
  • Fixed several issues that caused calendar events to not correctly synchronize when the server responded with HTTP status 400 ("Invalid sequence value").
  • Fixed a confusing log warning about proxy auto detection failure. The message now explicitly states that proxy auto detection errors can be ignored if you're not using a proxy.

Release notes for

December 6, 2019

What's fixed

Improved overload detection to reduce unnecessary attempts to sync the Global Address Book (GAL).

Release notes for

October 1, 2019

What's new
  • Improved the automatically-generated message that G Suite Sync posts to your Inbox when it finds problems in your profile. The message now contains a more detailed explanation with links to useful help center articles.
What's fixed
  • Fixed several issues that caused some users or contacts to not appear in the Global Address Book, or caused the Global Address Book to appear empty in Outlook.
  • Fixed an issue that caused Outlook to not show the sender's email addresses on the reading pane's header.
  • Fixed an issue that caused links in calendar event descriptions to not render correctly in Outlook.
  • Fixed an issue that prevented users from accepting meeting invitations or changing calendar events created with "Guest can modify event" enabled. 
  • Fixed an issue that caused HTML comments to appear in the description of a rich-formatted calendar event after a synchronization.

Release notes for and earlier

Earlier version release notes

May 22, 2019

What's fixed
  • Fixed an issue that caused messages to sync to the Archived email folder in Outlook if a user changed their Gmail labels using the Gmail web UI or the Android app. If you experience this issue, force a resync using the Overwrite option. For details, see Resync or repair Outlook data.
  • Fixed an issue that caused preview problems with attachments to messages in the Sync Issues folder.

April 23, 2019

What's new
  • Added support for incoming messages with UTF-8 headers. This option is disabled by default. To enable the option, see Enable support for incoming messages with UTF-8 headers.
  • GSSMO no longer asks to create a new profile after installation if one already exists.
  • Better handling of Gmail limit notifications. A detailed error response can be found attached to the corresponding Sync Issues messages.
  • Several logging improvements that help with diagnosing issues.
What's fixed
  • Fixed an issue that caused synchronization errors when forwarding a calendar event with an empty description.
  • Fixed an issue that caused synchronization errors when forwarding an occurrence of a recurring calendar event.
  • Fixed an issue that caused the sender and recipients' full names to not be displayed on sent event invites.
  • Fixed an issue that caused a sync failure to be reported when deleting an event in Outlook that was already deleted on Google Calendar.
  • Fixed an issue that caused additional plaintext conference data (automatically generated by Calendar for GSSMO) to appear stacked at the end of a calendar event HTML description in Outlook.
  • Fixed an issue that caused unwanted labels being created in Gmail for non-email Outlook folders.
  • Fixed an issue that caused synchronization failures when an iOS sync creates a "Notes" label in Gmail which conflicts with Outlook's built-in "Notes" folder.
  • Fixed an issue that prevented setup of a new profile being completed if an existing Outlook profile is corrupted.
  • Fixed multiple issues related to outdated Windows timezone mappings.

December 17, 2018

What's new
  • On December 31, 2018, we'll discontinue support for Windows XP and Windows Server 2003 platforms which are no longer supported by Microsoft. If you already have GSSMO installed on these platforms, GSSMO will continue to function but won't receive updates. If you're using an unsupported operating system, we encourage you to move to a newer version of Windows.
  • G Suite Sync posts messages to your Inbox with instructions on how to resolve folder synchronization issues, if problems are detected.
  • When you upgrade from an older version of G Suite Sync, GSSMO automatically scans your profile and notifies you if there are problems with some special Outlook folders.
What's fixed
  • Fixed an issue that caused calendar events to fail to synchronize if the busy status is set to Working elsewhere. The calendar events now appear as available in Google Calendar.
  • Fixed an issue that prevented the creation of a G Suite Sync profile when a Windows registry setting had an invalid value.
  • Fixed an issue that caused descriptions of calendar events in Outlook 2016 to lose line breaks.
  • Fixed an issue that caused notes synchronization messages to fill the Sync Issues folder if trace logging is set to Verbose.
  • Fixed an issue that stopped email being sent from a secondary IMAP account if the label Outbox existed on the Gmail account.

November 8, 2018

What's new

In the previous release, an issue was fixed that caused Outlook to move items from the Outbox folder to Sent Items without sending the messages to their recipients.

This release searches for unsent messages that have been incorrectly placed in the Sent Items folder. If unsent messages are found, an email giving instructions on how to recover the messages is posted in the user’s inbox.

October 10, 2018

What's fixed

Fixed an issue that caused Outlook to behave incorrectly if emails were sent when there was no network connection. Messages moved from the Outbox folder to Sent Items but weren't delivered to their recipients. These messages will now remain in Sent Items in Outlook and won't get synced to Sent Mail in Gmail.

August 6, 2018

What's fixed
  • Fixed an issue where users couldn't respond to an S/MIME message by using the Reply button.
  • Fixed an issue where GSMMO couldn't display free/busy information for some Global Address List contacts on the Scheduling view.
  • Fixed an issue that caused GSSMO to fail to synchronize if some registry values were set to the wrong type.

June 12, 2018

What's new

GSSMO now supports synchronization of rich text descriptions for calendar events. If you are using Outlook 2016, see In Outlook 2016, don’t save a calendar event with HTML format for details.

What's fixed

Fixed an issue that caused GSSMO to send duplicate emails when retrying due to network or proxy errors.

October 12, 2017

What's new

The logs contain more detailed network error messages, when connection failures occur.

What's fixed

Fixed an issue with MAPI to MIME conversion that prevented messages being sent if they had internationalized email addresses.

September 5, 2017

What's fixed
  • Fixed an issue where calendar exceptions to recurring events didn't sync between GSSMO and Google Calendar. 
  • Fixed an issue where GSSMO was prevented from authorizing access to the Google Account when Microsoft Edge was set as the default browser.

May 3, 2017

What's new
  • Google Apps Sync for Microsoft Outlook has a new name, G Suite Sync for Microsoft Outlook (GSSMO), and a new logo.
  • Better logging in cases where parsing the Contacts API response fails.
  • The list of third-party Outlook plugins is now reported in trace logs, to help with troubleshooting compatibility issues.
  • Notes folders that are deleted in Outlook will now be moved to Trash in Google Drive instead of being completely deleted.
What's fixed
  • Fixed an issue where the GSSMO Sync Status window wasn't visible after closing and restarting Outlook.
  • Fixed an issue where limited-access shared calendars—those with Permission Settings set to See only free/busy (hide details)—didn't sync properly.
  • Fixed an issue that occurred when a user attempted to rename a calendar that they no longer had write access to. This caused Outlook to crash.
  • Fixed an issue where network issues caused GSSMO to lose authorization. GSSMO continued to ask for authorization.
  • Fixed an issue where GSSMO didn't correctly ask for authorization after being de-authorized.
  • Improved user notification of a disabled/suspended account.
  • Fixed an issue where losing access to a delegated account prevented the primary account being used.
  • Removed unused Email Migration API scopes from OAuth authorization.
  • Updated OAuth2 endpoints. (Admins: See Troubleshoot network traffic issues to see whether your firewall or proxy needs to be updated).
  • Updated time zone mappings for proper synchronization of Calendar events in different time zones.
  • Updated Help Center article URLs.
  • Fixed some memory leaks.
  • Improved logging of some common sync and parsing failures for easier diagnostics.
  • Fixed an issue that caused a profile creation to fail in some cases if the Outlook language was changed after GSSMO is installed.
  • Fixed an issue where contacts with a birth year before 1601 (for example, if you use "82" instead of "1982") caused Contacts sync to fail completely. Now only the affected contact will fail to sync (because Outlook doesn't support years prior to 1601).

Release 3.8.440.1250
December 16, 2015

What's fixed

Fixed an issue that caused GASMO to keep asking for authorization when some of the services have been disabled by the Google Apps administrator.

Release 3.8.430.1200
December 2, 2015

What's fixed
  • GASMO didn't correctly handle a case where the OAuth token was no longer valid. It now asks the user to re-authorize if the OAuth token is revoked. 
  • The Delete saved GASMO passwords tool (ProfilePasswordDelete.exe) now works with Outlook 2016 Click-To-Run.

Release 3.8.420.1150
November 11, 2015

What's new
GASMO now supports Office 2016 and Windows 10.


Release 3.7.410.1100
May 19, 2015

What's fixed

Issue: When deleting a subfolder in the Outlook Notes folder, the Google Drive folder was permanently deleted, including non-Notes content.


  • Notes and Notes folders removed from Outlook are now sent to Trash in Google Drive instead of being permanently deleted.
  • Deleting a Notes folder from Outlook will move all Notes items in the Drive folder to Trash. If the Google Drive folder is empty (contains no other Drive documents), the empty folder is moved to Google Drive's Trash.

Release 3.7.400.1050
April 28, 2015

What's fixed

Improved Notes synchronization

Issue: Notes synchronization would crash the application if there were malformed responses returned by Drive API requests.

Resolution: Optimized Notes synchronization by limiting the fields requested of the Drive API to only those fields that are needed to perform the update.

Release 3.7.395.1040
March 24, 2015

What's fixed

Notes synchronization no longer crashes the application if there are missing or empty data fields returned in Drive API requests.

GASMO automatically updates so users will receive the new version over the following days. If you have disabled automatic updates, or if you installed a version that doesn't include automatic updates (the Enterprise MSI version of GASMO), you can get the latest version from our download page.

All customers who have opted not to auto-update must upgrade to GASMO 3.7.395.1040. Notes synchronization in older versions will stop functioning after April 20, 2015.

Release 3.6.390.1030
March 9, 2015

What's new

Google Apps Sync for Microsoft Outlook now uses the Drive API for Notes synchronization
(version 2).

GASMO automatically updates so users will receive the new version over the following days. If you have disabled automatic updates, or if you installed a version that doesn't include automatic updates (the Enterprise MSI version of GASMO), you can get the latest version from our download page.

All customers who have opted not to auto-update must upgrade to GASMO 3.6.390.1030 before April 20, 2015. Notes synchronization in older versions will stop functioning after this date.

What's fixed

Accounts with more than 100 calendars can now sync Google Calendar correctly.

Release 3.5.385.1020
October 20, 2014

What's fixed

Outlook sync version 3.2.353.947 and earlier clients are not prompted to re-authenticate after the tool is upgraded

Issue: Immediately after upgrading from version 3.2.354.947 or lower, user are not prompted to re-authenticate. As a result, the sync fails and requires the user to re-authenticate.

Resolution: The new version of the tool properly determines that re-authentication is required after upgrading from version 3.2.353.947 or lower.

Release 3.5.380.1010
September 19, 2014

What's fixed

Calendar event updates failed due to event sequence number complications

Issue: After a calendar event is updated, its sequence number is increased by a value of one. The GASMO tool was attempting to update the sequence number of a changed event twice, preventing the event changes from syncing to Google Calendar.

Resolution: The Outlook sync tool now only updates the sequence number of a changed event once. 

Release 3.5.375.1000
September 15, 2014

What's fixed

Messages sent in Outlook 2013 are not delivered to particular contacts

Issue: If you create a contact in Outlook 2013 by right-clicking on a message you've received and selecting Add to Contacts, subsequent messages sent to that contact will not be delivered.

Resolution: GASMO now fixes the contact's address in Outlook by registering it as a valid SMTP address. Any existing invalid contacts will be fixed with this upgrade.

Updated calendar events cause local calendar sync failures in Outlook

Issue: Outlook Sync users may receive a local calendar sync error after the owner of an event they've already accepted updates the meeting time.

Resolution: GASMO now properly handles changes to calendar event sequence numbers.

Release 3.5.370.990
February 20, 2014

What's fixed

Calendar sync issues

Issue: Some users experienced calendar sync issues when the calendar event feed included events that didn't have visibility, creator, and organizer provided.

Resolution: GASMO now syncs these events correctly even when visibility, creator, and organizer are missing.

Profile creation issues on Click-to-Run version of Outlook

Issue: Some users received errors when trying to set up a new GASMO user. Error codes 0x8007013d or 0x8007045a were visible in the trace log files.

Resolution: GASMO can now create profiles successfully on these system, without the need for any workaround.

Release 3.5.365.980
November 21, 2013

What's new

GASMO now supports Click-to-Run editions of Microsoft Outlook 2013.

What's fixed

Calendar sync issues

Issue: Events with dates between the years 100 and 1600 would cause the entire calendar to not sync.

Resolution: GASMO now syncs these events correctly: Events in years up to 0099 are treated as events in years 2000-2099, and events in years 100-1600 are treated as events in year 1601, which is the earliest year Outlook supports.

Release 3.4.360.960
September 26, 2013

What's new

"Remember me" is now checked by default to help ensure users don't have to go through authorization more than once.

What's fixed

Multiple prompts for authentication

Issue: Under certain scenarios, users are prompted for authentication multiple consecutive times, or when network issues occurred.

Resolution: GASMO now correctly stores authentication details during the session, and retries on network errors for two minutes.

Calendar sync issues

Issue: Events with dates prior to the year 1601 or with visibility set to "private" could cause the calendar to not sync.

Resolution: GASMO now parses these events correctly.

Appointments changing to meetings

Issue: Appointments (events with no attendees) would change to meetings (events with only the user as the single attendee) after being synced.

Resolution: Event type is now preserved.

Issues accepting invitations

Issue: In come cases, invitations to events sent from external systems (non-Google users) couldn't be accepted.

Resolution: All invitations can now be processed correctly.

Calendar invites would sometimes appear blank or have no RSVP buttons

Issue: When the recipient's email address didn't match the user's known email addresses in Outlook, RSVP buttons would be missing.

Resolution: RSVP buttons are now shown for all invitations.

Authorization errors

Issue: In some cases, issues detecting browser authorization would cause authorization to fail even when the user completed it.

Resolution: Better means of detecting browser authorization have been implemented.

GASMO profile creation issues

Issue: Users with suspended Google+ profiles were not able to create a profile.

Resolution: Profile creation now handles users with suspended Google+ profiles correctly.

Incorrect detection of the Outlook version

Issue: In some cases, the installation would report that an unsupported version of Outlook is installed even when it was a supported version.

Resolution: GASMO installation now checks the correct Registry keys and values to detect Click-to-Run versions of Outlook.

Release 3.3.355.950
June 3, 2013

What's fixed

Calendars with large number of events failed to sync

Issue: Some calendars with a large number of events failed to sync, instead returning errors after timing out.

Resolution: This problem has been fixed and should no longer occur. 

Release 3.3.354.948
May 22, 2013

What's new

Outlook 2013 support!

GASMO now supports Microsoft Outlook 2013.

Easily change trace file and PST file locations

By default, GASMO stores your trace files and Outlook PST files with your local application data in a Google/GASMO folder (details here). If you want to change these locations, you can now do so using a simple menu command. Just right-click GASMO in the Windows system tray and choose Modify PST and Log folder path.

Enhanced security via web-based Authorization

In previous versions of GASMO, users authorized their Outlook profile by entering their Google Apps user name and password in Outlook. To enhance security, users setting up their Outlook profile for the first time are now redirected to a web page where they're prompted to authorize using OAuth—an open standard authorization protocol. As a result, users can now remotely revoke access to GASMO from their web-based Account Settings, should their computer be lost or stolen.

What's fixed

Delegate's calendar events appeared on subscriber's calendar

Issue: Subscribing to receive another user's calendar notifications caused GASMO to create events for the subscriber even if they weren't invited to the event.

Resolution: GASMO no longer creates events for subscribers unless the subscriber is themself invited to the event.

Release 3.2.353.947
August 14, 2012

What's new

Simplified login when using SSO only

We've improved the login flow for GASMO users who have enabled single sign-on (SSO) login to Google Apps, but not Google password login.  The login dialog is simplified (shows only one option for entering a password), and the authentication landing page better redirects users back to the GASMO application.

Note: You enable or disable SSO vs. password login for individual users by making registry settings on the user's computer. Learn more

What's fixed

Address book error messages

Issue: Address book errors were being reported for domains that weren't using the Google Apps Global Address List (GAL). These errors were logged with a status code of 0x80041192.

Resolution: This status code is now disabled in the GASMO interface. Instead, for domains that aren't using the GAL, text appears stating that the service has been disabled by the administrator.  No errors are displayed or sync issues logged.

Delegate profiles were replacing primary user's display name in outgoing email

Issue: In some cases, adding a delegate to your Google Apps profile in Outlook would replace your primary user's display name in outgoing mail.

Resolution: This has been fixed and should no longer occur.

May 23, 2012

What's fixed

Sent messages incorrectly appeared as coming from the wrong user

Issue: If you had delegate access to your manager's Gmail account in GASMO, but sent a message from your own inbox, the message looked like it came from your manager (or whoever you had delegate access to). Your return address was correctly displayed, but your name incorrectly appeared as your manager's.

Resolution: All messages sent from your own inbox now display your correct name in the From field.

May 9, 2012

What's new

New registry key for hiding the Synchronization Status dialog for new users

You can now prevent the Synchronization Status dialog from opening by default when a new user first launches GASMO. This only applies the first time the user starts Outlook, after creating their Google Apps profile. You do this by creating a Windows registry key on the user's computer (do this before they create their Google Apps profile).

For details, see Configure options via the registry.

Disabled services are now indicated in the Synchronization Status

If a particular service such as Google Calendar or Google Drive is disabled for your domain, that service is now marked as disabled in the Synchronization Status dialog and GASMO doesn't try to sync items from that service.

What's fixed

Error reported when trying to run GASMO

Issue: In some cases, running GASMO displayed the error, "Unable to open your default email folders. The information store could not be opened." To use GASMO, you had to close Outlook and start it again.

Resolution: Several issues that were preventing GASMO from opening the folders have been fixed, and this error no longer occurs.

Lots of task errors were being logged in the Sync Issues folders

Issue: Some users were seeing consistent task sync errors logged in their Sync Issue folder.

Resolution: We improved how GASMO handles retryable server errors so you should see fewer of these errors logged in Sync Issues.

Release /
January 24 / March 9, 2012

What's new

Outlook Tasks now synchronize with Google Apps​!

You can use Outlook Tasks to track and manage to-do lists in your Google Apps account. The following information in Outlook Tasks synchronizes with your Gmail Task gadget, and is available from other devices where you access your Google Apps account:

  • Tasks, including due dates and reminders
  • Task state (whether a task has been marked as completed)
  • Top-level task folders sync as separate tasks lists in the Gmail Task gadget.


What's fixed

Contact sync errors occurred when using Outlook with Solve360

Issue: If you were using the Solve360 CRM client management service from the Google Apps Marketplace with GASMO, you might have been unable to sync your Contacts with Google Apps.

Resolution: Contacts now sync successfully when using Solve360.

Google, Google Workspace, and related marks and logos are trademarks of Google LLC. All other company and product names are trademarks of the companies with which they are associated.

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