Always On Availability Group Failover Issue
This error may happen if your SQL Server service is running under user who does not have the needed permission on your servers or the account is locked. try to use another account and make sure account is unlocked.

If that did not fix the issue then you need to edit your regisery (make sure you take a backup first)


open start menu,write regedit then press ok
navigate to HKEY_LOCAL_MACHINE\Cluster\Resources\&lt;GUID&gt;\Parameters 
Create the following registry values in the

Parameters registry key:

For a default instance of SQL Server: 
InstanceName 
Value Name: InstanceName 
Value Type: REG_SZ 

Value Data: MSSQLSERVER 

VirtualServerName 

Value Name: VirtualServerName 
Value Type: REG_SZ 

Value Data:  
For a named instance of SQL Server: 

Value Name: InstanceName 
Value Type: REG_SZ 

Value Data:  
VirtualServerName 

Value Name: VirtualServerName 
Value Type: REG_SZ 
Value Data:  


4- quit registery editor