...Installation will continue, but you may encounter an additional error "[(Microsoft] [SQL Native Client [SQL Server] Password Validation failed. The password does not meet the Windows policy requirements because it is too short.. To continue, correct the problem, and then run SQL Server Setup again." To correct this problem, open the Registry Editor.
Locate the key HKLM\SOFTWARE\Wow6432Node\Microsoft\Microsoft SQL Server\MSSQL.1\MSSQLServer\Parameters. Note that it may be MSSQL.2 or some other instance number instead of 1. For x86 operating systems, omit Wow6432Node from the registry path.
Create a string (REG_SZ) value named SQLArg3 and set the data to "-T4606" (no quotes). In response to the error message, cancel the installation and allow it to roll back. Then try the installation again.