Server Error in '/' Application.

Guid should contain 32 digits with 4 dashes (xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx).

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.FormatException: Guid should contain 32 digits with 4 dashes (xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx).

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace: 

[FormatException: Guid should contain 32 digits with 4 dashes (xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx).]
   System.GuidResult.SetFailure(ParseFailureKind failure, String failureMessageID, Object failureMessageFormatArgument, String failureArgumentName, Exception innerException) +4053805
   System.Guid.TryParseGuidWithDashes(String guidString, GuidResult& result) +14489412
   System.Guid.TryParseGuid(String g, GuidStyles flags, GuidResult& result) +238
   System.Guid.Parse(String input) +104
   WebPartProductPreviews.main.PopulateList(Int32 ItemSize, Int32& TotalRows) in c:\Programming\VirtualStore\VirtualStoreSystem\trunkmain\src-dev\WebPartProductPreviews\main.ascx.cs:736
   WebPartProductPreviews.main.OnPreRender(EventArgs e) in c:\Programming\VirtualStore\VirtualStoreSystem\trunkmain\src-dev\WebPartProductPreviews\main.ascx.cs:372
   System.Web.UI.Control.PreRenderRecursiveInternal() +132
   System.Web.UI.Control.PreRenderRecursiveInternal() +227
   System.Web.UI.Control.PreRenderRecursiveInternal() +227
   System.Web.UI.Control.PreRenderRecursiveInternal() +227
   System.Web.UI.Control.PreRenderRecursiveInternal() +227
   System.Web.UI.Control.PreRenderRecursiveInternal() +227
   System.Web.UI.Control.PreRenderRecursiveInternal() +227
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3671

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.8.4770.0