The error message suggests that the FILE adapter is having difficulty accessing the file share at \FILESERVER\SharedBizTalkIO\Prod\Queues\Invoices.
One possible cause of this issue could be that the file share is being locked by another process or application when BizTalk is attempting to access it. This could happen if another application or process is accessing the same file share at the same time as BizTalk, causing a lock on the file share.
To troubleshoot this issue, you could try the following steps:
Check if there are any other applications or processes that could be accessing the file share at the same time as BizTalk. For example, if there are any scheduled backups or maintenance tasks that run at the same time as the BizTalk receive location.
Check the permissions on the file share to ensure that the BizTalk service account has the necessary permissions to access the file share.
Check the network connectivity between the BizTalk server and the file share to ensure that there are no network issues that could be causing intermittent connectivity problems.
Enable debug logging on the FILE adapter to get more detailed information about the issue. You can enable debug logging by setting the following registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\BizTalk Adapter Pack\3.0\File\Debug Value: 1
This will create a log file in the following directory: C:\Program Files (x86)\Microsoft BizTalk Adapter Pack 3.0\File\log
The log file should provide more information about the error and could help pinpoint the root cause of the issue.