I'm running Windows 10 Pro, Version 1511 (Build 10586.545). I wanted to install the Xbox Accessories App, but got the error code 0x80240439 without any further details. As it turns out, I get that error when I try to install any app (which definitely did work at some point before).
I tried to investigate and found this in the Windows Update logs (a few lines are in german, sorry, but the gist should be understandable):
2016.09.08 00:08:55.2999858 676 792 WebServices Auto proxy settings for this web service call.
2016.09.08 00:08:55.6828367 676 792 WebServices WS error: Fehler beim Vorverarbeiten der Eingabequelle durch den XML-Reader in Zeile 1, Spalte 1300 (0x514).
2016.09.08 00:08:55.6828370 676 792 WebServices WS error: Ein Endelement wurde erwartet.
2016.09.08 00:08:55.6828373 676 792 WebServices WS error: Ein unerwartetes Startelement mit dem Namen CacheLifetimeMinutes" und dem Namespace "http://www.microsoft.com/SoftwareDistribution/Server/ClientWebService" wurde gefunden."
2016.09.08 00:08:55.6828381 676 792 WebServices Web service call failed with hr = 80240439.
2016.09.08 00:08:55.6828381 676 792 WebServices Current service auth scheme=0.
2016.09.08 00:08:55.6828384 676 792 WebServices Current Proxy auth scheme=0.
2016.09.08 00:08:55.6836675 676 792 SLS Retrieving SLS response from server using ETAG UODGUpPpKUSECGXeqbwPMdg0BYySCWk9UJebGlbHGPI=_1440"..."
2016.09.08 00:08:55.6837677 676 792 SLS Making request with URL HTTPS://sls.update.microsoft.com/SLS/{855E8A7C-ECB4-4CA3-B045-1DFA50104289}/x64/10.0.10586.0/0?CH=739&L=de-DE&P=&PT=0x30&WUA=10.0.10586.545
2016.09.08 00:08:56.6741275 676 792 Misc StatusCode for transaction returned from WinHttpQueryHeaders is 304
2016.09.08 00:08:56.6766369 676 792 Misc Got 855E8A7C-ECB4-4CA3-B045-1DFA50104289 redir Client/Server URL: https://fe3.delivery.mp.microsoft.com/ClientWebService/client.asmx""
2016.09.08 00:08:56.6777986 676 792 Misc Token Requested with 0 category IDs.
2016.09.08 00:08:56.6927945 676 792 Misc Acquired new token from Server
2016.09.08 00:08:56.6928651 676 792 Misc Got service 855E8A7C-ECB4-4CA3-B045-1DFA50104289 plugin Client/Server auth token of type 0x00000001
2016.09.08 00:08:56.6932602 676 792 ProtocolTalker PTError: 0x80240439
2016.09.08 00:08:56.6932613 676 792 ProtocolTalker SyncUpdates_WithRecovery failed. 0x80240439
2016.09.08 00:08:56.6932642 676 792 ProtocolTalker SyncUpdates round trips: 1
2016.09.08 00:08:56.6932644 676 792 ProtocolTalker Sync of Updates 0x80240439
2016.09.08 00:08:56.6932667 676 792 ProtocolTalker SyncServerUpdatesInternal failed 0x80240439
2016.09.08 00:08:56.6936103 676 792 Agent Failed to synchronize, error = 0x80240439
2016.09.08 00:08:56.6962830 676 792 Agent Exit code = 0x80240439
2016.09.08 00:08:56.6962835 676 792 Agent * END * Finding updates CallerId = WSAcquisition Id = 23
2016.09.08 00:08:56.6987966 6852 4772 ComApi *RESUMED* Search ClientId = WSAcquisition
2016.09.08 00:08:56.6990560 6852 4772 ComApi Updates found = 0
2016.09.08 00:08:56.6990563 6852 4772 ComApi Exit code = 0x00000000, Result code = 0x80240439
The first few lines sound like the XML response from a web service is invalid. How could that happen? I doubt that the Microsoft servers are returning incorrect data, so it's probably something on my device?
Best Answer
Apparently my Windows Update was broken in some still unknown way, and didn't update to the most recent Windows version. As Ramhound suggested, I manually updated by running the executable from http://go.microsoft.com/fwlink/?LinkID=799445, and then it worked.