Exceptions in a web app-dataview using

In one of our vb.net web applications, when a particular line of code is encountered, the following exceptions are thrown,

 

·         Collection was modified, enumeration operation might not execute

·         Object reference not set to an instance of an object

·         Value Cannot be null. Parameter name:Key

 

The line of code that’s responsible for these exceptions is:

 

Using DV As New DataView(DT) With {.RowFilter = "Cost = " & Cost}

 

And DT here is a datatable object.

The exceptions occur only when the application is accessed by 2 or more users at the same time.

 

If you have faced such issues before or know how to solve it, please let us know