Email Migration

Fix New-MailboxExportRequest Disk Latency and PST Export Failures

Emma Brown Sep 25, 2026 869 views

Question details

The user needs to resolve an issue where Exchange 2016 mailbox exports stall due to disk latency, resulting in failed exports and corrupted zero-length PST files.

Fix New-MailboxExportRequest Disk Latency and PST Export Failures

Product: Microsoft Exchange 2016
Device & OS: not provided
Scenario: Exporting mailbox data to PST files over a network share.
Observed behavior: The export requests fail with a StalledDueToSource_DiskLatency status, and some of the generated PST files contain zero-length headers.

Before you start

Ensure you have administrative access to the Exchange Server Management Shell and verify that your destination network share has sufficient storage space and proper write permissions.

Solution 1Recommended

Clear Corrupted PST Files and Reduce Simultaneous Exports

Remove remnants of failed exports and reduce the number of concurrent mailbox export requests to alleviate source storage strain.

The StalledDueToSource_DiskLatency error indicates that the Exchange database or storage system is being throttled due to heavy I/O loads. Creating too many simultaneous export requests can overload the system and cause the process to stall, leaving behind empty or corrupted PST files.

Locate destination share

Open the network destination folder where the mailbox export requests are configured to save the PST files.

Delete zero-byte files

Find any PST files that show a file size of 0 bytes or have incomplete headers, and permanently delete them to prevent conflicts during retry.

Review active requests

Open the Exchange Management Shell and run the command 'Get-MailboxExportRequest | Get-MailboxExportRequestStatistics' to view the status of all current requests.

Remove stalled requests

Clear the stalled jobs by running 'Remove-MailboxExportRequest' for the affected mailboxes.

Queue exports sequentially

Use the 'New-MailboxExportRequest' command to restart the exports, but limit the batch to 1 or 2 simultaneous requests to avoid triggering latency throttling again.

Clear Corrupted PST Files and Reduce Simultaneous Exports

Microsoft Q&A Consultation: For highly complex database architectures or persistent throttling issues, it is recommended to consult Exchange Server specialists on Microsoft Q&A for detailed queue-management guidance.

Solution 2

Check Exchange Database and Storage Latency

Investigate underlying disk latency on the Exchange server to ensure the storage system can handle the read operations required for exporting.

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Frequently Asked Questions

What does StalledDueToSource_DiskLatency mean in Exchange?

This status means that the Exchange Server's storage system is experiencing high read latency. To protect the performance of active user mailboxes, Exchange's resource management automatically throttles or pauses background tasks like PST exports.

Why are my exported PST files showing zero bytes?

Zero-length PST files are usually remnants of a failed or stalled export request. The file shell is created on the destination network share, but because the export process was throttled or interrupted, no actual mailbox data was written to it.

How do I clear failed mailbox export requests?

You can clear them using the Exchange Management Shell. First, run 'Get-MailboxExportRequest -Status Failed' to identify the jobs, and then pipe that into 'Remove-MailboxExportRequest' to delete them from the queue.

Can I bypass throttling for PST exports in Exchange 2016?

While it is possible to temporarily adjust Workload Management policies or use the '-Priority' parameter to prioritize a request, completely bypassing throttling is not recommended during peak hours as it can severely degrade database performance for end users.

Migration & Recovery