Validation of viewstate MAC failed

Posted on 2011-03-02
Last Modified: 2012-06-21

this error is making me crazy:

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.

I have tried the work around like enableViewState="false" viewStateEncryptionMode="Never", even i did not use the DataKeyNames property of the ListView.

I am having Asp.Net 3.5 and working in C# and getting this error in LIVE environment.

Please suggest any proven/used method to sort out this issue.

Kaushal Arora
Question by:Kaushal Arora
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LVL 52

Expert Comment

by:Carl Tawn
ID: 35015799
Is you app actually running in a cluster/farm environment?
LVL 12

Author Comment

by:Kaushal Arora
ID: 35016046
No It is not running in a cluster/farm environment. I am having a dedicated server for the application.

Expert Comment

ID: 35016131
Does this error only happen in IE or other Browsers as well?

I had this issue when I used jQuery to update some areas inside a web form by AJAX (only in IE, all other Browsers worked fine). Moving the AJAX-modified areas out of the <form runat=server>-tag solved the problem. Not the best solution, but in my case it worked.

Still looking for a more elegant solution though...
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LVL 12

Author Comment

by:Kaushal Arora
ID: 35016332
I am getting this error in all the browsers, not only in IE.
Also the error is coming on both type of pages that is where AJAX toolkit is used and where it is not.

LVL 16

Expert Comment

by:Kamal Khaleefa
ID: 35146577
try to add this string in <system.web> section of your web.config file :
<pages validateRequest="false" enableEventValidation="false" viewStateEncryptionMode ="Never" />
for fix "Validation of viewstate MAC failed" error.

also see this
LVL 12

Author Comment

by:Kaushal Arora
ID: 35146672
@king2002: I have already tried these things.

One thing more which i have observed is that mainly this error comes when my page is idle for some time and user click on any link.
LVL 16

Accepted Solution

Kamal Khaleefa earned 500 total points
ID: 35146813
The reason for this error is validation of Viewstate failing because of different value of key for encryption/decryption across different server on farm. Below link provide good explanation of this error and possible resolution for the same.
LVL 12

Author Comment

by:Kaushal Arora
ID: 35147548
I will test the second method given in the link and will revert you soon.

Thanks for the help.
LVL 12

Author Closing Comment

by:Kaushal Arora
ID: 35163821

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