another one of those errors that can appear in your ULS logs which can easily be solved. This error also logs events in the Application eventlog with ID 6398 and 5586.
I found the solution to this issue on the SharePoint forum here
This happens when you have the Usage and Health Data Collection Service Application installed. This service application creates a database just for logging. Apparently the Search Service was trying to make entries in that database and couldn’t.
The solution to this issue is to enable the Usage Data Collection, which is not enabled by default when you create the Usage and Health Data Collection Service Application .
To enable the Usage Data Collection navigate to Central Admin\Application Management\Service Applications\Manage service applications. Once there highlight the WSS_UsageApplication (or whatever name you gave the service application)and select manage from the ribbon. Under Usage Data Collection check the box. Under Health Data Collection check the Enable health data collection box. Hit OK and the errors will be gone.
Now that I am finalizing some of my farm installation I am starting to pay attention to those small issues reported by the Health Analyzer.
One of those errors in there is the following:
Title Missing server side dependencies.
Severity 1 – Error
Explanation [MissingWebPart] WebPart class [8d6034c4-a416-e535-281a-6b714894e1aa] is referenced  times in the database [SP2010_ContentDB_CentralAdmin], but is not installed on the current farm. Please install any feature/solution which contains this web part. One or more web parts are referenced in the database [SP2010_ContentDB_CentralAdmin], but are not installed on the current farm. Please install any feature or solution which contains these web parts.
To get rid of this error you simply need to configure the SharePoint Foundation Search service though the Central Admin – Services on Server page on one of the servers in the farm.
Once this is configured, the error will go away.
UPDATE: on one of my other farms I noticed this error and configured the SharePoint Foundation Search service (which oddly enough once configured, changes its name to SharePoint Foundation Help Search)
a little more research and some Google results later I found an answer to this problem posted on the technet forums by John D Palm stating:
“This error will appear on a cleanly installed system in the Health Analyzer Reports until you visit the following pages:
These are: Central Administration, General Application Settings, Farm Search Administration and then Search Service Application.
Browse to them and the error will no longer appear in the Health Analyzer Report.”
I followed John’s advise and indeed the error went away just after having visited both these pages and hitting the Reanalyze now button on the alert.
So there you go
Like everything in SharePoint why make things simple if you can make it hard
Turns out that if you want the RSS Viewer webpart, you need to activate the “SharePoint Server Standard Site Collection features” feature in your site collection first.
Took me about 10 minutes of snooping around in the Web part gallery and trying ta add a new one, before I figured that one out.
Thanks to Craig Lussier for answering this exact question on the Technet Forum.