This article desribes how to handle issues you can run into when extending windows server hard disks on ESXi.
In this perticular case the C:\ Partition should be extended from 139GB to 156GB.

After the extending the disk the C:\ Partition to 156GB the Explorer and Monitoring still show that the volume size is 139GB.




Always check that there is enaugh disk space remaining on the storage.
If a full storage is not the cause of this issue, keep looking.

A reboot always is a good idea, however in a production envoirement that is not always possible and does not help in this case.
A good trick is to extend the harddrive for one more GB.

After a refresh of the disk management utility using F5 there should be 1GB that is showing as “unallocated”.

After extending the volume again, issues like this are normally solved.

Do not wonder that the harddrive is showing as 156GB angezeigt wird…

… this is Windows, and there is a 100MB reserved partition in front of C:\ and the explorer only counts full GB.