Encryption validation error when upgrading to K2 5.6

 When upgrading to K2 5.6, you may run into an Encryption Validation error that stops the upgrade and puts it in a 'Recover' stage:

Error in the installer trace log indicates:

However, after the K2 database was migrated, the following script was already completed to drop and re-add encryption:

OPEN MASTER KEY DECRYPTION BY PASSWORD = 'passwordhere'; 

ALTER MASTER KEY DROP ENCRYPTION BY SERVICE MASTER KEY; 

ALTER MASTER KEY ADD ENCRYPTION BY SERVICE MASTER KEY; 

CLOSE MASTER KEY;

And the following does show that data is property decrypted:

OPEN SYMMETRIC KEY SCSSOKey 

DECRYPTION BY CERTIFICATE SCHostServerCert; 

SELECT [VariableToken],

       CONVERT(nvarchar(max), DECRYPTBYKEY([VariableValue])) as 'Decrypted Value',

    [VariableValue]

    FROM [HostServer].[Configuration]

WHERE [Encrypted]=1

The issue was due to the [K2HOSTCONNECTIONSTRING_SYSTEM] row in the HostServer.Configuration table not being encrypted, but the [Encrypted] column was set to 1.

To resolve you can run:

UPDATE [HostServer].[Configuration]

SET [Encrypted] = 0

WHERE [VariableToken] = '[K2HOSTCONNECTIONSTRING_SYSTEM]'

And then re-run the Setup Manager and perform the 'Recover' option.  Once the upgrade is completed, this row should be properly encrypted again.