If you see this error, it means that the reported number of emails that were exported do not match the number of emails that were expected.
This is often the case because Google does not always report accurate information with respect to the number of emails exported.
If the mismatch is an acceptable number, you can proceed by adding the following parameter to your Google Vault Extractor command:
-missingEmailThreshold xxx
Important: The xxx value needs to be replaced by a value that is less than or equal to the number of missing items.
The following is an excerpt from a Google Vault Export. In this case, the expected number of emails is one more than the actual number of emails, therefore, the parameter -missingEmailThreshold could be added with a value of 1.
Excerpt:
<3028:1:> Information: Checking export timeouts. Total emails: 314588 lastReportedNumberOfEmails: 314587 lastEmailExportedTime: 10/29/2016 23:41:46
<3028:1:> Error: EX: BitTitan.GoogleVaultExport.Export.GoogleVaultException: Mismatch in number of emails export for user: xxxxxx@domain1.com for Export :exportly-b2b349ed-f344-43d1-807c-cc9440c2a49a From matter :39f329f6-1be8-44d0-9f8a-b9d6a8162504. Expected 314588 emails but only got 314587 emails.
BitTitan.GoogleVaultExport.Export.GoogleVaultException: Mismatch in number of emails export for user: xxxxxx@domain1.com for Export :exportly-b2b349ed-f344-43d1-807c-cc9440c2a49a From matter :39f329f6-1be8-44d0-9f8a-b9d6a8162504. Expected 314588 emails but only got 314587 emails.
<3028:1:> Error: "BitTitan.GoogleVaultExport.Export.GoogleVaultException: Mismatch in number of emails export for user: xxxxxx@domain1.com for Export :exportly-b2b349ed-f344-43d1-807c-cc9440c2a49a From matter :39f329f6-1be8-44d0-9f8a-b9d6a8162504. Expected 314588 emails but only got 314587 emails.", ExponentialRetryStrategy: Retry failed.
BitTitan.GoogleVaultExport.Export.GoogleVaultException: Mismatch in number of emails export for user: xxxxxx@domain1.com for Export :exportly-b2b349ed-f344-43d1-807c-cc9440c2a49a From matter :39f329f6-1be8-44d0-9f8a-b9d6a8162504. Expected 314588 emails but only got 314587 emails.
at BitTitan.GoogleVaultExport.Export.GoogleVaultExport.WaitForExportCompletion(String email) in D:\BuildAgent\work\28f980e36f2601b3