Error:

Problem:

By default “Spell check” button uses “AjaxSpellCheck” not “SpellCheck “

  <telerik:EditorTool Name="SpellCheck" Enabled="true" />

Solution:

Use AjaxSpellchek

   <telerik:EditorTool Name="AjaxSpellCheck" Enabled="true" />

Error Message:

Timeout expired.  The timeout period elapsed prior to completion of the operation or the server is not responding.

Reason:

Default execution timeout value in SQL Studio is 30 seconds

Solution:

Increase the execution & connection timeout value while opening new query window(File --> New --> Database Engine Query)

ASP.Net 4.5 introduced more options to the Text Mode property: Color, Date, DateTime, DateTimeLocal, Email, Month, Number,Range, Search, Phone, Url, Week

But remember all these new options will work only with browsers supporting these HTML5 features (Ex: IE 10). For all other browsers these textbox's will behave as normal textbox.

Ps: Here is a nice website, where you can test your browser HTML5 features: http://html5test.com/

Problem:

RadEditor Content not saved on page postback.

Solution:

Add UseSubmitBehavior="false" to the button that’s causing page postback.

<asp:Button ID="Button1" runat="server" 
OnClick="Button1_Click" Text="Button1"  UseSubmitBehavior="false"  />

Check out compilify.net . It allows you to quickly and easily execute snippets of C# code from your browser.

   <asp:CollapsiblePanelExtender ID="cpeTest" runat="server" TargetControlID="Panel1"
                                            CollapsedSize="0"
                                            Collapsed="True"
                                            ExpandControlID="lbutton1"
                                            CollapseControlID="lbutton1">

 cpeTest.ClientState = "true";
 cpeTest.Collapsed = true;

If you want to read one book about Asp.Net security, read OWASP Top 10 for .NET developer by Troy Hunt

                There’s a harsh reality web application developers need to face up to; we don’t do security very well. A report from WhiteHat Security last year reported “83% of websites have had a high, critical or urgent issue”. That is, quite simply, a staggeringly high number and it’s only once you start to delve into to depths of web security that you begin to understand just how easy it is to inadvertently produce vulnerable code.

Error Message:

Could not find any resources appropriate for the specified culture or the neutral culture.  Make sure "AjaxControlToolkit.Properties.Resources.NET4.resources" was correctly embedded or linked into assembly "AjaxControlToolkit" at compile time, or that all the satellite assemblies required are loadable and fully signed.

Reason:

AjaxControlToolkit’s control load reference refers to the base System.Web.UI.Control method which is present as a part of the ASP.NET AJAX Libraries and those libraries are referenced only when the ScriptManager is referenced in the page.

Solution:

Add ScriptManager in the page and this error would be resolved.

            <asp:ScriptManager ID="ScriptManager1" runat="server">
            </asp:ScriptManager>

   List<string> liItems= (from ListItem item in ListBox1.Items where item.Selected select item.Value).ToList();

This diagram shows the high-level architecture of PerformancePoint Services in Microsoft SharePoint Server 2010 Enterprise.