When running an asp web site in production, my users frequent fail to be able to save entered information to a page throwing a Null Reference Exception because the stored session variables had been cleared. This would be normal providing the user had went beyond the 20-minute default session timeout value, but these continually occur long before the session timeout. It had become a problem when the IIS and SQL 2012 servers were converted to a server farm with virtual server, but I had changed the application web.config to include the line <sessionState mode="SQLServer" allowCustomSqlDatabase="true" sqlConnectionString="Data Source=CFCO06DEVSQ100;Database=ASPState;User ID=XXXXXXXXXX; Password=XXXXXXXX" timeout="120" />
but still it is looking like the session state is still dropping the session variables when the physical server changes. Can someone advise where else to look or add to prevent this from happening?