Suddenly an automation script has parsing errors, and I'm not quite sure why it's suddenly giving this error or how to resolve it.

Message : Automation script 'Sencore Video PID set' failed to execute (ScriptErrorType: ErrorType) : (after retries) (Code: 0x80040251) Skyline.DataMiner.Net.Exceptions.DataMinerException: No Assembly found for cookie 5
(40,23): error CS8179: Predefined type 'System.ValueTuple`2' is not defined or imported
(40,72): error CS8179: Predefined type 'System.ValueTuple`2' is not defined or imported
(40,54): error CS8179: Predefined type 'System.ValueTuple`2' is not defined or imported
(46,17): error CS8179: Predefined type 'System.ValueTuple`2' is not defined or imported
(47,21): error CS8179: Predefined type 'System.ValueTuple`2' is not defined or imported
(67,62): error CS8179: Predefined type 'System.ValueTuple`2' is not defined or imported
(67,51): error CS8179: Predefined type 'System.ValueTuple`2' is not defined or imported
(99,8): error CS8137: Cannot define a class or member that utilizes tuples because the compiler required type 'System.Runtime.CompilerServices.TupleElementNamesAttribute' cannot be found. Are you missing a reference?
(99,8): error CS8179: Predefined type 'System.ValueTuple`2' is not defined or imported
(99,38): error CS8179: Predefined type 'System.ValueTuple`2' is not defined or imported
(99,38): error CS8179: Predefined type 'System.ValueTuple`2' is not defined or imported
(27,9): warning CS0219: The variable 'valuesServiceId' is assigned but its value is never used
(29,7): warning CS0219: The variable 'tempId' is assigned but its value is never used
(226,18): warning CS1701: Assuming assembly reference 'mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' used by 'Interop.SLDms' matches identity 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' of 'mscorlib', you may need to supply runtime policy
(230,4): warning CS1701: Assuming assembly reference 'mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' used by 'Interop.SLDms' matches identity 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' of 'mscorlib', you may need to supply runtime policy

The script has following imports

using Skyline.DataMiner.Automation;
using Skyline.DataMiner.Net.Messages;
using Interop.SLDMS;
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;

It also has following dll references
System.Linq.dll
System.Core.dll
C:\Skyline DataMiner\Files\Interop.SLDMS.dll