Dynamics NAV - Message: An item with the same key has already been added.

Problem:
This error occurs after a separate NAS service has been started.
The service itself runs, but the window error log shows this error, and the NAS does not execute any scheduled tasks.



Solution:
Google has Vague descriptions about problems with duplicate language codes, or duplicate keys in tables.

It may have to do with sql security after restoring a db to a new sql server that has the same user accounts, but in caps or commons.
Remove all users from the db and re-add them to ensure the security on the db corresponds to the actual users on the machine.

Set SQL to run as the same account the NAV Instance is running under
Ensure the account is a member of db_owner in the company db

Run the Fix Orphan Script
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SET NOCOUNT ON
USE AdventureWorks
GO
DECLARE @loop INT
DECLARE @USER sysname
DECLARE @sqlcmd NVARCHAR(500) = ''

IF OBJECT_ID('tempdb..#Orphaned') IS NOT NULL
 BEGIN
  DROP TABLE #orphaned
 END

CREATE TABLE #Orphaned (UserName sysname,IDENT INT IDENTITY(1,1))

INSERT INTO #Orphaned (UserName)
SELECT [name] FROM sys.database_principals WHERE [type] IN ('U','S') AND is_fixed_role = 0 AND [Name] NOT IN ('dbo','guest','sys','INFORMATION_SCHEMA')

IF(SELECT COUNT(*) FROM #Orphaned) > 0
BEGIN
 SET @loop = 1
 WHILE @loop <= (SELECT MAX(IDENT) FROM #Orphaned)
  BEGIN
    SET @USER = (SELECT UserName FROM #Orphaned WHERE IDENT = @loop)
    IF(SELECT COUNT(*) FROM sys.server_principals WHERE [Name] = @USER) <= 0
     BEGIN
        IF EXISTS(SELECT 1 FROM sys.database_principals WHERE [Name] = @USER AND type_desc = 'WINDOWS_USER')
         BEGIN
            SET @sqlcmd = 'CREATE LOGIN [' + @USER + '] FROM WINDOWS'
            Exec(@sqlcmd)
            PRINT @sqlcmd
         END
        IF EXISTS(SELECT 1 FROM sys.database_principals WHERE [Name] = @USER AND type_desc = 'SQL_USER')
         BEGIN
            SET @sqlcmd = 'CREATE LOGIN [' + @USER + '] WITH PASSWORD = N''password'''
            Exec(@sqlcmd)
            PRINT @sqlcmd
         END
     END
   
    SET @sqlcmd = 'ALTER USER [' + @USER + '] WITH LOGIN = [' + @USER + ']'
    Exec(@sqlcmd)
    PRINT @USER + ' link to DB user reset';
    SET @loop = @loop + 1
  END
END
SET NOCOUNT OFF

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