Showing posts with label ASP.Net C# Errors. Show all posts

May 19, 2012

'Operation is not valid due to the current state of the object' error during postback

12:13 AM vikram reddy No comments

'Operation is not valid due to the current state of the object' error during postback

I had a aspx page which was working well, but suddenly I am getting the error "Operation is not valid due to the current state of the object." whenever a postback is done.

The stack trace is:

at System.Web.HttpValueCollection.ThrowIfMaxHttpCollectionKeysExceeded()
at System.Web.HttpValueCollection.FillFromEncodedBytes(Byte[] bytes, Encoding encoding)
at System.Web.HttpRequest.FillInFormCollection()

Solution:

<appSettings>
<add key="aspnet:MaxHttpCollectionKeys" value="10000" />

</appSettings>

AsyncFileUpload "Cannot Access A Closed File" exception

6:37 AM vikram reddy No comments

Add following code in web.config:

<system.web>

No http handler was found for request type 'GET'

10:23 AM vikram reddy No comments

This is what you need for ASP.NET 4.0 / IIS 7.5 on Windows 7:

Your web.config must contain the following:

<appSettings>
  <add key="ChartImageHandler" value="storage=file;timeout=20;" />
</appSettings>

<compilation targetFramework="4.0">
 <assemblies>
  <add assembly="System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
 </assemblies>
</compilation>
<system.webServer>
<handlers>
      <add name="ChartImg" verb="*" path="ChartImg.axd"  type="System.Web.UI.DataVisualization.Charting.ChartHttpHandler, System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"  />
    </handlers>
</system.webServer>

You also need this at the top of your aspx page:

<%@ Register Assembly="System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
    Namespace="System.Web.UI.DataVisualization.Charting" TagPrefix="asp" %>

Object cannot be cast from dbnull to other types

1:16 AM vikram reddy No comments

This is a common error that you get when trying to display a field with no value (null), from a table.
Sol:
Convert.IsDBNull(dt.Rows[i]["Pass1"]) ? null : dt.Rows[i]["Pass1"].ToString();