Operation is not valid due to the current state of the object.

Error : Operation is not valid due to the current state of the object.

Stack Trace:

[InvalidOperationException: Operation is not valid due to the current state of the object.] System.Web.HttpValueCollection.ThrowIfMaxHttpCollectionKeysExceeded() +2692482 System.Web.HttpValueCollection.FillFromEncodedBytes(Byte[] bytes, Encoding encoding) +61 System.Web.HttpRequest.FillInFormCollection() +148 [HttpException (0x80004005): The URL-encoded form data is not valid.] System.Web.HttpRequest.FillInFormCollection() +206 System.Web.HttpRequest.get_Form() +68 System.Web.HttpRequest.get_HasForm() +8743911 System.Web.UI.Page.GetCollectionBasedOnMethod(Boolean dontReturnNull) +97 System.Web.UI.Page.DeterminePostBackMode() +63 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +133

This error occurs when form fields are very large in numbers.By default, the maximum value of MaxHttpCollection is 1000.

Solution:

To solve this error, increase MaxHttpCollection value. Try adding the following setting in your web.config's <appsettings> block. 

<appSettings>
        <add key="aspnet:MaxHttpCollectionKeys" value="3000" />
 </appSettings> 

you can change the value accordingly as per your need. 

Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster

Here are few steps to fix "Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster" error.

Step 1 : Visit this link and generate your machine key.
http://www.eggheadcafe.com/articles/GenerateMachineKey/GenerateMachineKey.aspx

Step 2 : Copy the machine key given by above link and paste it to your web.config file.


<?xml version=”1.0″?>

<configuration>

    <appSettings/>
    <connectionStrings/>
    <system.web>

       <machineKey validationKey='4C8B22744D71B73CE6B16262A97CF3862E584829229EDE45C9DF207DDF5F3507782A3F2F6506085028628868F6AFFC25D16BE4AD8BB677637B11C892F95FE819'   decryptionKey='53EA49CFEC5C5A1E4720DE83E1CC75337674757144EB1DCB'   validation='SHA1'/>

    </system.web>
</configuration>


Step 3 : By doing above two steps you will be relieved by this error.But you must know why this error occurs.To get a good detail about this error you must visit this link.

http://www.codeproject.com/Articles/16645/ASP-NET-machineKey-Generator

error code 0x8007045D

Meaning of Error 0x8007045d is "ERROR_IO_DEVICE" i.e. "The request could not be performed because of an I/O device error. There are various cause for this error like :

1.  May be the brand of the disc is incompatible with the burner.
2. May be the disc is defective.Use another one .
3. May be the burner have malfunctioned.

In summary, "error code 0x8007045D" simply means the media is bad.