Extpart.exe error "Unable to connect to C: or it does not exist"

When you try to expand C: drive using extpart.exe you get the following error:
"Unable to connect to C: or it does not exist"

Here are some workarounds you can try:

1. Close Windows Disk Management console. It's using Logical Disk Management service which extpart.exe is using.
2. Make sure there are no snapshots
3. Stop some non-essential services i.e:

• Windows Search
• File Replication service
• DFS Replication service
• Perfect disk PDEngine service

4. Reboot computer in safe mode and then run extpart.exe