When you are deploying a “big” software update like KB2919355, with System Center Configuration Manager, you can have the error code 0x800f0821 on some computers.
The computer receives the update, downloads it and starts to install it but the installation will fail.
This error is raised because the execution time was reached. Depends on computers and servers, you may or not have this error on all SCCM clients.
Let’s see how to change the configuration in SCCM.