There are a couple of things you can try... such as
You may already have restored this site before. In that process you also deleted the site first (automatically), which you can find running the command...
>Get-SPDeletedSite
You'll see the site (or sites) listed, like this:
WebApplicationId : 009c1289-392b-43a6-8222-146117074738
DatabaseId : 88efc46f-5a2b-4171-81cb-7577da65bac3
SiteSubscriptionId : 00000000-0000-0000-0000-000000000000
SiteId : 86d69f7e-3a9e-4f65-8eba-550d77f93a18
Path : /sites/collaboration
Scheme : Http
Url : http://portal/sites/collaboration
DeletionTime : 2014-02-21 11:14:18
WebApplicationId : c73bb367-d329-4ef2-aef7-323ce207d2a9
DatabaseId : aeb2d6ab-9f9b-493f-aefc-797d4b591f43
SiteSubscriptionId : 00000000-0000-0000-0000-000000000000
SiteId : 9d0ed313-0353-4cec-817a-a491a8c5fc26
Path : /
Scheme : Http
Url : http://portal/
DeletionTime : 2014-02-19 15:27:37
Copy the SiteId
and run
Remove-SPDeletedSite –Identity 9d0ed313-0353-4cec-817a-a491a8c5fc26
That way you won't have trouble deleting the site upon restore (which is the first thing that happens).
Depending on your scope, this may or may not be a way to move forward. It's not applicable to hundreds of SPWebs, since it will take you too long time to perform. But for a few SPWeb objects, this works very well. And if you're targeting a specific web to "move" to your development environment, then this is a good alternative to Backup/Restore-SPSite.
Start by exporting the SPWeb object. You'll get the subsites as well, but won't get workflows in your export.
>Export-SPWeb http://site –Path "C:\Backup\site-export.cmp"
Switch to your restore (import) site and execute
>Import-SPWeb http://site –Path "C:\Backup\site-export.cmp" –UpdateVersions Overwrite
I use this method when Restore-SPSite fails the way you describe.
3. Database attach method
>Restore-SPFarm -Directory <BackupFolder> -RestoreMethod Overwrite -Item <ContentDatabase> [-BackupId <GUID>] [-Verbose]
Where:
If you do not use the BackupId parameter, the most recent backup will be used. To view all of the backups for the farm, type the following command at the Windows PowerShellcommand prompt:
>Get-SPBackupHistory -Directory <Backup folder>
Reference: Restore content databases in SharePoint 2013