Hi,uploading the procmon log kept dropping, so I checked for the presence of the 2 updates listed in the other post, one was missing, KB4490628 so I downloaded from MS catalog and installed it. After that the monthly rollup update downloaded and installed ok. It seems you managed to fix the previous problems I had, but the SHA-1 / SHA-2 issue was the reason that KB4512506 wasn't installing. I will advise if there are any problems after a restart, and confirm what happens at the next monthly rollup. Many thanks for your help, really appreciated !