Source Message failures and cannot create row, duplicate key error messages
Any Version of 5 and some of 6x. Issues like this cannot be fixed completely without an upgrade to latest and run the sanitize tool.

If you see these messages in the log (and sometimes they are silent failures) these may occur on these previous versions because older versions of Add2Exchange did not employ SQL transaction logic and when the server was rebooted during the synchronization processing or you did a Microsoft® update without stopping the Add2Exchange Service prior and rebooting afterwards, the older version filled the table with partially completed rows. The newer versions of Add2Exchange have transaction processing technology and indexing to avoid this from happening going forward, but best practices are you should still stop the Add2Exchange Service prior to any reboot or Microsoft update to be safe.

To fix the issue, you must be running the current version.
• Go to the Downloads area on our website to upgrade to the newest release.
• MAKE SURE you select the correct version you are licensed for -- Standard or Enterprise Edition.

Before you install it, please go into the Add2Exchange Console and make sure you have valid software subscription (date expires today or in the future) and then get the new version for free or if it is expired, you will have to purchase a Current Version Upgrade license prior to installing.
Upgrade instructions here.

You will also need to run the sanitizedb utility, prior to opening the Add2Exchange Console. Located here:
ftp://ftp.diditbetter.com/A2EDiags/sanitizedb.exe

More information: http://support.diditbetter.com/kb/A2E_183.aspx.

Errors this utility fixes are messages in the log which look similar to the following, and running the sanitize will fix them:

Event 1004 Add2Exchange Synchronization FAILURE source message: John. of Relationship: Public - EMP Contacts To John Collins - Contacts

Event 9997 20100426123653: FAILURE_1: RC <> 0. A2EMsgObjectSRC.saveMessageObject method failure to save message object for Destination Message. | Calling program: A2ESP

Then open up the Console. There may be a pause where it says it is creating the indexes. Let it continue even though it may say not responding. When the Console opens, you can continue as normal, your system is not updated and stable. While in the Console, check for to make sure licensing is current. If the Console drops, open it again.

If you are making changes to your Exchange environment, use this link to correct it for the new configuration: http://guides.diditbetter.com/a2e-guide/index.html (see Exchange Configuration). The same service account configuration is required for both Standard and Enterprise versions. You should use the same account as you did before the migration or addition of newer Exchange Server versions, just make the configuration changes to the existing account. For Exchange 2007 and Exchange 2010, there is a new Preinstaller (or a handy permissions changer for existing accounts) located in the new download. This automatically gives the correct permissions and greatly simplifies the Exchange Shell commands needed. Instructions are located here: http://support.diditbetter.com/kb/A2E_214.aspx

Effects on synchronization:
The effect of having invalid rows in the database allowed by prior versions is that some deleted items may come back and/or some changed items may revert (just once) after the rows are deleted. What happens in a specific environment is determined by the kind of relationships set up in the Add2Exchange Console.

Deleting the invalid rows does not directly change the source or destination folders, just the meta data (data about the data) information A2E uses to determine what do on edits and deletes of an item. Saving the information will do nothing either, but people needed that option to feel safer.

These items with invalid rows were not replicating correctly anyway, and once the invalid rows are deleted, after just two complete sync cycles, the normal rules of the replication relationship will work as designed again. The first sync may revert a change to another users changed copy in a bidirectional relationship which may not be the intended result.

The tips here are to stop the A2E Service, upgrade to the latest MS Critical Service packs and then (always) reboot, then make sure you download and run the latest version of diditbetter.com software, and then run the sanitize DB tool as soon as possible.

As a convenience, we can assist and remotely log in as a Level 2 support session ($199)  Buy Now and make sure it works correctly for you. We will also do it at no charge if you have purchased a Premier Support plan ($399 for 4 hours)  Buy Now. Again, this type of enhanced remote services are not covered under your standard software subscription services. Software Subscription services entitles you to free upgrades and free email support for your licensed solution.

We appreciate your business and look forward to assisting you and we apologize for the problems this may have caused.

We appreciate your business and look forward to working with you.