Details about the error you see:
NullReferenceException Class (System) | Microsoft Docs[
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Quote:
A NullReferenceException exception is thrown when you try to access a member on a type whose value is null
Possibly because:
1. You've forgotten to instantiate a reference type
2. You've forgotten to dimension an array before initializing it.
3. You get a null return value from a method, and then call a method on the returned type.
4. You're using an expression (for example, you're chaining a list of methods or properties together) to retrieve a value
5. You're enumerating the elements of an array that contains reference types, and your attempt to process one of the elements throws
6. Exception is thrown by a method that is passed null
Following will help you learn about debugging:
Tutorial: Debug Visual Basic code - Visual Studio | Microsoft Docs[
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First look at the debugger - Visual Studio | Microsoft Docs[
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When you debug, you will be able to get the exact line where the variable is NULL and error is being raised. Handle the case and you will be able to resolve it.
To start with, in the code shared above, all the lines where you are doing
Convert.ToString
are potential possible culprits.
Try out!