Question

uncaught exception: [Exception…
“‘Sys.WebForms.PageRequestManagerServerErrorException:
Sys.WebForms.PageRequestManagerServerErrorException:
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.’ when calling method:
[nsIDOMEventListener::handleEvent]”
nsresult: “0x8057001c
(NS_ERROR_XPC_JS_THREW_JS_OBJECT)”
location: “JS frame ::
chrome://firebug/content/spy.js ::
callPageHandler :: line 744” data: no]

Thing is, I don’t even have a machineKey tag. I commented it out and I still get this error.

This is my entire web.config file:

<?xml version="1.0"?>

<configuration>
  <configSections>
    <sectionGroup name="UrlRewriter">
      <section name="PlainRules" type="System.Configuration.NameValueSectionHandler"/>
      <section name="RegExRules" type="System.Configuration.NameValueSectionHandler"/>
    </sectionGroup>
  </configSections>

  <UrlRewriter>
    <PlainRules configSource="UrlRewriter.plain.config" />
    <RegExRules configSource="UrlRewriter.regex.config" />
  </UrlRewriter>

  <connectionStrings configSource="db.config"/>

  <system.net>
    <mailSettings>
      <smtp configSource="mail.config"/>
    </mailSettings>
  </system.net>

  <system.web>
    <!--<machineKey validationKey=""
                decryptionKey="" validation="SHA1" />-->

    <compilation debug="true" targetFramework="4.0" />
    <globalization culture="en-US" uiCulture="en" requestEncoding="UTF-8" responseEncoding="UTF-8" fileEncoding="UTF-8" />
    <trace enabled="false"/>
    <!--<customErrors defaultRedirect="~/error" mode="RemoteOnly"/>-->
    <httpRuntime maxRequestLength="4000" executionTimeout="1000"/>

    <authentication mode="Forms">
      <forms defaultUrl="~/" loginUrl="~/login" timeout="43200" protection="All"  cookieless="UseCookies" />
    </authentication>

    <membership defaultProvider="AspNetSqlMembershipProvider" hashAlgorithmType="SHA1">
      <providers>
        <clear/>
        <add name="AspNetSqlMembershipProvider" type="System.Web.Security.SqlMembershipProvider" applicationName="damnation" connectionStringName="membership"
             enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="true" passwordFormat="Hashed"
             maxInvalidPasswordAttempts="20" minRequiredPasswordLength="4" minRequiredNonalphanumericCharacters="0" passwordAttemptWindow="5"
        />
      </providers>
    </membership>

    <roleManager defaultProvider="AspNetSqlRoleProvider" enabled="true">
      <providers>
        <clear/>
        <add name="AspNetSqlRoleProvider" type="System.Web.Security.SqlRoleProvider" connectionStringName="membership" applicationName="damnation"/>
      </providers>
    </roleManager>

    <profile defaultProvider="AspNetSqlProfileProvider" enabled="true" inherits="Damnation.Website.Shared.Membership.SharedMembershipProfile">
      <providers>
        <clear/>
        <add name="AspNetSqlProfileProvider" type="System.Web.Profile.SqlProfileProvider" connectionStringName="membership" applicationName="damnation"/>
      </providers>
    </profile>

    <httpModules>
      <add name="UrlRewriter" type="Damnation.Website.Shared.UrlRewriting.UrlRewriterModule"/>
    </httpModules>
  </system.web>

  <system.webServer>
    <validation validateIntegratedModeConfiguration="false"/>

    <modules runAllManagedModulesForAllRequests="true">
      <add name="UrlRewriter" type="Damnation.Website.Shared.UrlRewriting.UrlRewriterModule"/>
    </modules>
  </system.webServer>
</configuration>

What could be the issue here?
I should also mention that I tried with and without the rewriter (small module I wrote myself), so that’s not the issue either here…

Update: this issue is caught by firebug when I try to login with membership, which causes a postback in an updatepanel.

Answer 1

If you don’t have a machineKey in your config, its using the one from machine.config.

Is this site setup on a web farm? If so you should generate a machineKey and put it in all the web.config file installations for your site.