I have searched high and low on this error, but my problem stems back to which control is causing this problem.
In theory the problem starts when someone goes to a specific tab and clicks a button to download a PDF file. After doing that if I use a dropdownlist the error pops up.
I have checked the code etc. just cannot figure out which control is triggering the error.
Can anyone help so I can identify the control that is the problem?
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