Troubleshooting; Section on always using UTF-8 in Windows.

Troubleshooting.md

@@ -1,3 +1,28 @@
+# Program won't start
+
+## Last logged "Locale LC_ALL: ..."
+
+If you're using EDMC 4.1.0 or later (including betas) you might find the
+program fails to start with the last line in the [Debug Log File]() being
+something like:
+
+```
+2020-09-20 22:54:03.164 - DEBUG - EDMarketConnector.__main__:1071: Locale LC_ALL: ('Russian_Russia', '1251')
+```
+
+As per [Issue 771: 4.1.0-beta5 can't start](https://github.com/EDCD/EDMarketConnector/issues/711)
+this is caused by a Windows problem and has [a workaround](https://stackoverflow.com/a/61937729):
+
+1. Go to **Control Panel**, not Windows Settings.  You might need to search
+for 'Control Panel' in the Start Menu.  Alternatively.
+    1. Go to `Control Panel\All Control Panel Items` in a File Explorer window.
+1. Open `Region`
+1. Click `Administrative` tab.
+1. Click `Change system locale...` (it's the button in the second section
+ "Language for non-Unicode programs").
+1. Tick the box "Beta: Use Unicode UTF-8 for worldwide language support".
+1. Click "OK".  You'll probably be prompted to reboot for this to take effect.
+
 # Problems with Frontier Authentication
 
 ## App repeatedly opens the Frontier authentication website