DNN 4.6.0 Upgrade and Whitespace Filter Errors
As noted in my previous blog posting I have upgraded this website to be running DotNetNuke 4.6.0. Prior to the upgrade this site was running DNN 4.5.2 and I performed a direct upgrade to 4.6.0. Also as I mentioned in my previous posting the upgrade didn't go all that smooth, with the site being down for almost an hour as I worked out the "bugs" that I identified with the 4.6.0 upgrade. This article will discuss one of the issues that I encountered relating to the Whitespace Filter.
First of all to give a little background as all of you are aware this site had been up and running on 4.5.2 since shorlty after it was released, the site was first created as a DNN 4.3.7 site, then upgraded to 4.4.1 when it came out, then to 4.5.0 and 4.5.2. The reason I mention this is that I am NOT 100% sure what the root cause was for this issue, so I am not 100% sure if it is a true "bug" in the upgrade process as a whole or if there is a specific series of events that had occured beforehand that made the situation worse.
Previously I had my website performance settings configured to store cache information in memory with heavy caching. I had compression turned off and I had the whitespace filter turned on. The whitespace filter configuration was 100% standard DNN with no modifications. When I performed the site upgrade the entire upgrade went off without any errors or warning messages. When I navigated to my website after the upgrade I was greeted by the standard .NET exception message referring to "object reference not set to an instance of an object" The full stack trace is below.
[NullReferenceException: Object reference not set to an instance of an object.]
DotNetNuke.HttpModules.Compression.WhitespaceFilter.Write(Byte[] buf, Int32 offset, Int32 count) +104
System.Web.HttpWriter.Filter(Boolean finalFiltering) +251
System.Web.HttpResponse.FilterOutput() +60
System.Web.CallFilterExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +29
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +64
Looking at this stacktrace I was able to instantly identify the WhitespaceFilter as the culprit, luckly there was an easy fix. Since the site was unusable at this point in time I used the following SQL query to turn off the filter.
UPDATE HostSettings
SET SettingValue = 'N'
WHERE SettingName = 'WhitespaceFilter'
After executing this script I was able to fully view the site and all functionality has been restored. I have not yet been brave enough to re-enable the filter, but I have been informed that it does work! Hopefully this can help you resolve the issue quickly if you encounter it! Please share your comments below!
Posted by Mitchel on Wednesday, September 19, 2007
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