If you are getting 0x80070643 error while doing windows update, this may be because of downloaded setup files are corrupted.
There were some problems installing updates, but we’ll try again later. If you keep seeing this and want to search the web or contact support for information, this may help: (0x80070643)
To fix this error, move latest downloaded files from “C:\ProgramData\Package Cache” to another backup folder. To do this, sort this folder by “Date Modified” and move the folder that has the same date.
Then if you try Windows Update again, error would be gone and Windows Update would install the updates.
Note: If this doesn’t work, move back those backed-up folders back…
Vardars Blog 