I'm trying to figure out this error but I can't point out what's exactly causing this.
Here is what's happening.
User loggs in for a few hours and gets "Validation of viewstate MAC failed" Error after post back.
I have set timeout in Web.config as follow.
<forms timeout="540" slidingExpiration="true" loginUrl="~/maintain/login.aspx" />
in IIS I have set
ApplicationPool - Idle Time-out 60min
Sesstion State - Cookei Settings Mode: User Cookies, Time-out: 540min
And I'm using this ifame to prevent Idle
Emplyee logges in for 8 hours and having this issue a few time a day...
Do you know what else I should look?
I don't know why session expires.
Thank you for your help
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