The 0x800f0900 error occurs when you try to install cumulative updates for Windows 10. Windows 10 Update Error Code 0x800f0900 translates to CBS_E_XML_PARSER_FAILURE which indicates that some system files related to the update process are corrupted. In this article, we will discus the major causes of this Windows 10 Update 20H2 Error 0x800f0900 and the solution needed to resolve this Windows 10 Update Error Code 0x800f0900.