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Obtained error: Object reference not set to an instance of an object.

Posted on 2014-01-29
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Last Modified: 2014-05-05
Server Error in '/' Application.
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drpRegions is set correctly but the 'Object reference not set to an instance of an object.' error is obtained

Object reference not set to an instance of an object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:


Line 550:        Dim plantRowItem As dsPlants.tblPlantsRow
Line 551:        For Each plantRowItem In dsPlants.tblPlants
Line 552:            If ((plantRowItem.RegionCode.ToString() = drpRegions.SelectedItem.Value.ToString()) _
Line 553:            And (plantRowItem.CellCode.ToString() = drpCells.SelectedItem.Value.ToString()) _
Line 554:            And ((drpPlants.SelectedIndex <> -1) And (plantRowItem.PlantName.ToString() = drpPlants.SelectedItem.Value.ToString())) _
 

Source File: C:\Inetpub\QSIRegister\QSIStage1.aspx.vb    Line: 552

Stack Trace:


[NullReferenceException: Object reference not set to an instance of an object.]
   ReadymixQSI_ASPNET.QSIStage1.SetMgrs() in C:\Inetpub\QSIRegister\QSIStage1.aspx.vb:552
   ReadymixQSI_ASPNET.QSIStage1.drpCells_SelectedIndexChanged(Object sender, EventArgs e) in C:\Inetpub\QSIRegister\QSIStage1.aspx.vb:601
   ReadymixQSI_ASPNET.QSIStage1.Page_Load(Object sender, EventArgs e) in C:\Inetpub\QSIRegister\QSIStage1.aspx.vb:290
   System.Web.UI.Control.OnLoad(EventArgs e) +131
   System.Web.UI.Control.LoadRecursive() +65
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2427

 


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Version Information: Microsoft .NET Framework Version:2.0.50727.5448; ASP.NET Version:2.0.50727.5420
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Question by:shanthi_joseph
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7 Comments
 
LVL 18

Expert Comment

by:Dennis Aries
ID: 39821671
Several options come to mind here:
Is there a selected item?  Has the regioncode been set?

Assuming you cannot use breakpoints: for debugging,  create several helper variables and set them to the values you use.
That way you will see which item gives you the problem and add checks accordingly to overcome the issue.
0
 
LVL 22

Expert Comment

by:p_davis
ID: 39821677
you should still, probably, make sure to check that selecteditem has a value before referencing it.

drpRegions.SelectedItem.Value.ToString())
0
 
LVL 21

Expert Comment

by:Craig Wagner
ID: 39821766
As the other responders have indicated, there are several things in that line that could be null.

If ((plantRowItem.RegionCode.ToString() = drpRegions.SelectedItem.Value.ToString()) _

plantRowItem could be null
RegionCode could be null
drpRegions could be null
SelectedItem could be null
Value could be null

Use the debugger and check each of the above values to figure out which one of them is actually causing the exception.
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Author Comment

by:shanthi_joseph
ID: 39828637
I am not able to use object as a parameter in MsgBox. How do we check if the object is null?
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Accepted Solution

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shanthi_joseph earned 0 total points
ID: 40033812
I do not require a solution for this problem.
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Author Closing Comment

by:shanthi_joseph
ID: 40041609
I do not require a solution to this problem.
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