i think this might be related to the Meltdown mitigation changes in memory management in windows…
When trying to install newly released updates for some software i get the message:
ShellExecuteEx failed; code 299. Only part of a ReadProcessMemory or WriteProcessMemory request was completed
while Avast is intercepting and scanning the process.
(screenshots in attachment)
the executable is https://www.virustotal.com/en/file/0a0d5c87983612154088014eb9bca92698355457c506aff3afa2ca9fc6afb3d2/analysis/