Recently while expanding the disk size on a Windows Server 2012 R2 VM, we received an error message pop-up saying “the parameter is incorrect”. We noticed that Disk Management was now showing the correct updated disk size but the incorrect original (smaller) size was still showing in windows explorer properties and in server manager.
We resolved this by extending the filesystem using the DISKPART utility – See Microsoft KB on this (note this was for Server 2003 but same method in 2012 R2 and probably 2008 R2) https://support.microsoft.com/en-us/kb/832316 – The partition size is extended, but the file system remains the original size when you extend an NTFS volume
Open command prompt
Type “list volume”
Type “select volume #”
Type “extend filesystem”