The form cannot be displayed because session state is not available

Scenario:
You got the following error while associating a workflow that uses InfoPath form.

Error : The form cannot be displayed because session state is not available.

Solution:
Check you Web.config and Uncomment the Session tag in HTTPModules section like this

Before:

<httpModules>
   <clear />
   <add name="SPRequest" type="Microsoft.SharePoint.ApplicationRuntime.SPRequestModule, Microsoft.SharePoint, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" />
   <add name="OutputCache" type="System.Web.Caching.OutputCacheModule" />
   <add name="FormsAuthentication" type="System.Web.Security.FormsAuthenticationModule" />
   <add name="UrlAuthorization" type="System.Web.Security.UrlAuthorizationModule" />
   <add name="WindowsAuthentication" type="System.Web.Security.WindowsAuthenticationModule" />
   <add name="RoleManager" type="System.Web.Security.RoleManagerModule" />
   <!-- <add name="Session" type="System.Web.SessionState.SessionStateModule"/> -->
   <add name="PublishingHttpModule" type="Microsoft.SharePoint.Publishing.PublishingHttpModule, Microsoft.SharePoint.Publishing, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" />
 </httpModules>

After:

 <httpModules>
   <clear />
   <add name="SPRequest" type="Microsoft.SharePoint.ApplicationRuntime.SPRequestModule, Microsoft.SharePoint, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" />
   <add name="OutputCache" type="System.Web.Caching.OutputCacheModule" />
   <add name="FormsAuthentication" type="System.Web.Security.FormsAuthenticationModule" />
   <add name="UrlAuthorization" type="System.Web.Security.UrlAuthorizationModule" />
   <add name="WindowsAuthentication" type="System.Web.Security.WindowsAuthenticationModule" />
   <add name="RoleManager" type="System.Web.Security.RoleManagerModule" />
   <add name="Session" type="System.Web.SessionState.SessionStateModule"/>
   <add name="PublishingHttpModule" type="Microsoft.SharePoint.Publishing.PublishingHttpModule, Microsoft.SharePoint.Publishing, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" />
 </httpModules>