If you have issues with SCCM deployed software updates failing to download and install, try checking the UpdatesHandler.log file (I recommend using trace32.exe with the SCCM Toolkit).
The particular problem I experienced, resulted in the following lines being written to the UpdatesHandler log: –
Unable to get locations, no need to continue with download
CBundledUpdate — Failed to download update (1a5ada44-c5cd-11de-a7e1-001372775900). Error = 0x80040669
CDeploymentJob — Failed to download update (1a5ada43-c5cd-11de-a7e1-001372775900). Error = 0x80040669
Note that these are seperate log entries, and are not written consequetively.
In this case, expand the Software Updates node in the appropriate Deployment Package in which the update is stored, locate the failed update and click on the Content Information tab (there will most likely be multiple updates with the name Article ID for different operating systems).
Individually selecting each of the updates that match the Article ID, ensure that all of the relevant files with unique Content IDs are marked as downloaded (i.e. in the Downloaded column it reads Yes).
There may be Content IDs for different languages, and these can be ignored.
If there are records with unique Content IDs that are not downloaded, the update should be re-downloaded and re-deployed using the usual method.