I'm getting the exact same error...
It would seem transferring to this forum did not give this question any more attention!
This error code shows up even if I de-select all the updates available and only update the (non-selectable) Adobe Application Manager.
Download completes and Red Triangle Exclamation Point appears stating "Some updates failed to install."
Internal window states: "There was an error uploading. Please quit and try again later. Error Code: U43M1D207"
Customer Support "Chat" was of no service either, they are ill equipped to deal with this issue and refered me to product support. The question becomes: What Product?
Please show me where to find the CS5 Adobe Application Manager update support forum!