Ajax site do Cross Page Postback but get: Object reference not set to...

I think it is feasible to redirect to another web page through setting thePostBackUrl?property of a asp:Button.
Try to set a breakpoint at line #9 and check if the value of?nextKeyexists.If it is null,you will get "Object reference not set to an instance of an object" exception when the codes of Line #11 and Line #12 are executed. If this happens,you need to debugpostedValuesand check if it is correct.

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