Search in Discovery Accelerator fails with an error stating the search has been abandoned with an unrecoverable error.

Problem

Any Discovery Accelerator (DA) search fails with the Information column containing a message stating there were items or content missing from the index volume.

Error Message:

On DA client below error is received:

The search has been abandoned with an unrecoverable error. Items or content missing from Index.

Event viewer on DA server shows the below warning:

Source:        Accelerator Service Processor
Event ID:      42086
Description:
APP AT - Customer ID: 2 - Warning:
Some items could not be searched:
Archive: XXX
ID: xxxxxxxxxx
Index Volume: 56789
Search ID: 1234
Description:
Items or content missing from the index
Reason: Items or content missing from the index

Cause

When a DA search is run, the search criteria are passed to the Enterprise Vault (EV) Indexing Service on the EV server hosting the index volumes of the archives that have been configured to be searched.  If an index volume contains items that could not be indexed, such as encrypted messages or attachments or items that could not be recalled to be indexed, the index volume search will return what items match the search criteria but with the Information column containing an error message stating that there are items or content missing.  By default, this will not cause a search to be marked as failed but a configuration setting can be changed to cause such a search to be listed as failed.

Solution

Change the configuration setting back to the default value by following the below steps:

1. Launch the DA Client with an account that has the Application level permission Modify System Configuration granted through a Role assignment.  The Vault Service Account should have this permission by default.
2. Click on the Configuration tab.
3. Click on the Settings sub-tab.
4. Expand the Search section.
5. Locate the option Error search if missing items or content.
6. In the Value column of this option will be a box containing a check mark.  Clear that check mark.
   1. Note - If the there is a need to know who changed this setting and when it was changed and before changing it back to being unchecked, look in the two right-most columns of the option's line to see when and who made the change.
7. Click the Save button.
8. A pop-up dialog box will appear stating that the Customer Background Tasks must be restarted.  Click the OK button to acknowledge this required action.
9. Close the DA Client.
10. Log onto the DA server as the Vault Service Account.
11. Launch Internet Explorer (IE) or Microsoft Edge to the EVBAAdminm site: http://localhost/EVBAAdmin.
12. In the left panel, left-click on the Customer name to see its properties in the right panel.  Note that the DA server name will be listed at the top of this panel and may have a plus (+) sign to its left to indicate it needs to be expanded to see the listing of DA Customers running under that server.
13. Right-click on that customer to see a selection of options appear.
14. Select the Customer Background Tasks option.  Note that a check mark in the left column of that option's selection will be present.
15. Monitor the Customer's tasks: line in the right panel to see it change from Running to Stopping and then to Stopped.
16. After the status is Stopped, right-click on the customer name and select the Customer Background Tasks option again.  Note that no check mark in the left column of that option indicates the option is stopped.
17. Monitor the Customer's tasks: line in the right panel again to see it change from Stopped to Starting and then to Running.
18. Once the Customer's tasks: line shows Running, close the browser and log off of the DA server.
19. Launch the DA Client again.
20. Run a new search against the archive to see complete with a Finished status for each index volume but with the Information column showing the items or content missing information.

More info about the setting Error search if missing items or content:

This option is designed to allow control of what happens to a search when any index volume against which the search runs contains items that could not be indexed.  By default, such a search will complete and be able to be accepted in to the DA Case's Review Set with any index volume having items or missing content.  When this option is enabled, any search of any archive with items or content missing error will cause the search to be set to a failed state and cannot be accepted into the Review Set of the DA Case.