As I found out, this problem not only affects KeePass, but all (Windows) services that use HTTP, too. Therefore, I adapted my original question.
The specs:
- Win10 v1709, all the latest updates
- .NET Framework 3.5 & 4.7 checked in Windows Features
World Wide Web Services&IIS Management Consolechecked in Windows Features- Services are set up like out-of-the-box
Visual Studio Community 2017with.NET desktop development- No CCleaner/manual registry "tweaks" whatsoever
The first thing that I noticed was that KeePass 2's HTTP-Plugin stopped working after updating KeePass (this does not make much sense, but I did nothing else at that time).
Now, when starting KeePass 2, it throws the following error:
The .NET HttpListener is not supported on your OS
The KeePassHttp-Plugin now refuses to work with browser-plugins.
Later on, I found out that all services that require HTTP Service - which is not listed in my Services Window - stopped functioning. So for example, the Print Spooler service stopped working. When I try to start it it says:
Windows could not start the Print Spooler service on Local Computer. Error 1068: The dependency service or group failed to start.
Error 1068 is displayed on all those services. I googled it, but found no (working) solution.
I tried sfc /scannow, booting into Safe Mode, enabling/disabling all services - all to no avail. Also, DISM does not show any corruptions.
Another lead was No http service - Windows 10:
C:\> sc qc http [SC] QueryServiceConfig SUCCESS SERVICE_NAME: http TYPE : 1 KERNEL_DRIVER START_TYPE : 2 AUTO_START ERROR_CONTROL : 1 NORMAL BINARY_PATH_NAME : system32\drivers\HTTP.sys LOAD_ORDER_GROUP : TAG : 0 DISPLAY_NAME : HTTP Service DEPENDENCIES : SERVICE_START_NAME :C:> sc queryex http SERVICE_NAME: http TYPE : 1 KERNEL_DRIVER STATE : 1 STOPPED WIN32_EXIT_CODE : 183 (0xb7) SERVICE_EXIT_CODE : 0 (0x0) CHECKPOINT : 0x0 WAIT_HINT : 0x0 PID : 0 FLAGS :
C:> sc start http [SC] StartService FAILED 183: Cannot create a file when that file already exists.
C:> net start http System error 183 has occurred. Cannot create a file when that file already exists.
C:> sc queryex spooler SERVICE_NAME: spooler TYPE : 110 WIN32_OWN_PROCESS (interactive) STATE : 1 STOPPED WIN32_EXIT_CODE : 1068 (0x42c) SERVICE_EXIT_CODE : 0 (0x0) CHECKPOINT : 0x0 WAIT_HINT : 0x0 PID : 0 FLAGS :
C:>sc start spooler [SC] StartService FAILED 1068: The dependency service or group failed to start.
System error 183 seems to be a lead, but unfortunately, Google provided little help in resolving this.
Also, Event Viewer revealed nothing new (in my opinion):
See this link for the XML of all HTTP-related events (all of them were warnings, by the way). All of them recur after a restart.
Apart from performing a clean install (or at least one of Win10's reset options), is there some option to get things running again?

