SQL Server Failover cluster instance upgrade failure issue from 2008 R2 to 2012

Today, one of my clients' production environment was facing an issue with the failed upgrade of a SQL Failover Cluster Instance from SQL 2008 R2 to SQL 2012. They were trying the upgrade since a couple of days and it was failing with the below error

TITLE: SQL Server 2008 R2 Setup
------------------------------
The following error has occurred:
The search for mount points failed. Error: The system cannot find the path specified.
For help, click: http://go.microsoft.com/fwlink?LinkID=20476\&ProdName=Microsoft+SQL+Server\&EvtSrc=setup.rll\&EvtID=50000\&ProdVer=10.50.6000.34\&EvtType=0xF7F8ABE1%25400x1C2074D8%25401216%25401
------------------------------
BUTTONS:
OK
------------------------------

On checking the summary.txt logs of the Setup Bootstrap found the below information :

Detailed results:
Feature: Database Engine Services
Status: Failed: see logs for details
MSI status: Passed
Configuration status: Failed: see details below
Configuration error code: 0x1C2074D8@1216@1
Configuration error description: The search for mount points failed. Error: The system cannot find the path specified.
Configuration log: C:\Program Files\Microsoft SQL Server\100\Setup Bootstrap\Log\20180813_084025\Detail.txt
Feature: SQL Server Replication
Status: Failed: see logs for details
MSI status: Passed
Configuration status: Failed: see details below
Configuration error code: 0x1C2074D8@1216@1
Configuration error description: The search for mount points failed. Error: The system cannot find the path specified.
Configuration log: C:\Program Files\Microsoft SQL Server\100\Setup Bootstrap\Log\20180813_084025\Detail.txt
Feature: Full-Text Search
Status: Failed: see logs for details
MSI status: Passed
Configuration status: Failed: see details below
Configuration error code: 0x1C2074D8@1216@1
Configuration error description: The search for mount points failed. Error: The system cannot find the path specified.
Configuration log: C:\Program Files\Microsoft SQL Server\100\Setup Bootstrap\Log\20180813_084025\Detail.txt

Thus based on the error message probed the client around the fact if there were any kind of directory changes since the last upgrade and they provided the information that the backup directory was changed and the disk was changed but it was not updated on the Backup registry value under the following registry hive:

Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\MSSQL10.MSSQLSERVER\MSSQLServer\

Post changing that and provided the local administrator account for the below User Rights Assessment :

Act as Part of the Operating Sywstem = SeTcbPrivileg
Bypass Traverse Checking = SeChangeNotify
Lock Pages In Memory = SeLockMemory
Log on as a Batch Job = SeBatchLogonRight
Log on as a Service = SeServiceLogonRight
Replace a Process Level Token = SeAssignPrimaryTokenPrivilege

These two action items helped us resolve the issue. Thus the upgrade went smooth and the client team was happy.

Hope this helps !! Happy Upgrading!!