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Validation of viewstate MAC failed - 9.10.12+

KC Cook Dynamicweb Employee
KC Cook


Running into an issue on multiple sites where we receive a "Validation of viewstate MAC failed" error after trying to save changes to settings in the backend. I've primarily seen the error when making changes to security settings but have heard from others it happens with other sections as well. We've tested on a couple different 9.10.12 sites and one that was 9.10.16. An example site would be:
Here is the error we receive:

Thank you,



Oleg Rodionov Dynamicweb Employee
Oleg Rodionov


We are in research the cause of the issue and will comment it a bit later. There already was forum related to issue like this, the error exception has link for details, please have a look as well. Sorry for inconvenience.

BR, Oleg QA

Nicolai Pedersen

It is not a DW issue, but a hosting issue.

Google the exception and read the link that is given in the exception.
BR Nicolai


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