Use PowerShell

I got the same error. But I was able to create the Managed Metadata Service application using PowerShell.New-SPMetadataServiceApplication -ApplicationPool "SharePoint - Managed Metadata" -Name "Managed Metadata Service - Apps" -DatabaseName "Managed_Metadata_Apps" -DatabaseServer "MyDBServer" New-SPMetadataServiceApplicationProxy -Name "Managed Metadata Service - Apps" -ServiceApplication "Managed Metadata Service - Apps" -DefaultProxyGroup