Running Docker for Windows, Error when exposing Ports

Here's a new twist.

The last Windows 10 update (Fall Creators Update, 2017) has a new "feature". It automatically starts any applications that were running when you last shutdown.

This reconstitutes Docker for Windows in a bad state. That made it appear those ports were in use by something else - it was the ghost of itself. This explained why those ports were still in use even though I stopped/started my containers and even reboot!

The solution in this case is to simply restart Docker daemon.

To prevent this after the next shutdown, don't use the shutdown button. Type this instead:

shutdown /s /t 0

This bypasses the new feature.

See the answer from Jason[MS] in this thread:

https://answers.microsoft.com/en-us/insider/forum/insider_wintp-insider_perf-insiderplat_pc/programs-autostart-after-boot-in-windows-10-fall/09dd8d3e-7b36-45d1-9181-6587dd5d53ab

Here's one guy's workaround (from the end of this thread - haven't tried it myself):

http://www.icttoolbox.nl/info/stop-windows-10-creator-fall-reopening-programs-reboot/

Restarting the Docker daemon fixes this problem temporarily, but to get rid of it ultimately I had to disable Windows 10 fast startup, which is the feature @biscuit314 described.

To disable Windows 10 fast startup, get to the Control Panel > Power Options > Choose what the power buttons do > Change settings that are currently unavailable > Uncheck Turn on fast startup (recommended) and hit Save changes

This is caused by a port numbering conflict: github issue here https://github.com/docker/compose/issues/3277

Essentially the port is in use! The reason resetting worked is because it wiped other mappings off.