This appears to be more of a problem with Exchange than with DP
I checked lab cases for this error, and found none. Then, I googled' the error, and got one hit
new-mailboxrestorerequest -sourcedatabase rdb -sourcestoremailbox a -targetmailbox a -skipmerging storageproviderforsource
what happened was the above command restored the mailbox. it did not skipped the merging, so i was not able to see the restore folder in OWA.
I refreshed the page many times but there was no Restore folder because it was merged with the original mailbox
To create a restore request, you must provide the DisplayName, LegacyDN, or MailboxGUID for the soft-deleted or disabled mailbox. To get a list of mailboxes you can restore run Get-mailboxStatistics –Database Testrestore
Error detail: must be logging in with GUIDs. not legDN. I tried with the DisplayName, LegacyDN and MailboxGUID without success.
But I found another parameter I could use: -SkipMerging StorageProviderForSource.
and it worked
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By no means should I be considered a Exchange expert, and you shoud run this past teh Exchange administrator before trying it. Also, I don't know how this would figure into Exchange GRE restore, since the documentation does not show any where where a login is required