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Validation of viewstate MAC failed in asp.net | More On

We may sometimes encounter the following error:

To make sure that the ViewState data is not changed, every viewstate data that is exchanged between the client and the server is verified. A distinct key is used for the encryption and decryption of the ViewState data. There won’t be any problems if the app runs on a single computer because the encryption and decryption processes always require the same key. However, since this key value varies throughout the servers in web farms, this won’t be the case.

How to Fix it?

Solution 1

We must change the EnableViewStateMac to false in the web.config:. EnableViewStateMac is the attribute of the Page tag that comes under the . It may appear as:

Solution 2

Another solution is to set the EnableViewStateMac to false at the page level as below:

However, this must be done for every page in the program. Therefore, if we have to implement it on a huge application with many pages, it becomes a highly time-consuming task.

Solution 3

The last solution is to specify our own value for encryption and decryption in the web.config file. Then, we can create a machine key via the Unique Machine KeyGenerator. The new key will be the same across all the servers. For e.g;

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Conclusion

To sum up, we provide 3 troubleshooting methods for the Validation of viewstate MAC failed in the asp.net issue.