If NVDA is unable to communicate with a braille display (e.g. because…

… it has been disconnected), it will automatically disable use of the display.

This eliminates problems such as excessive log file size and lag when this occurs.

source/braille.py

@@ -1308,7 +1308,11 @@ def _displayWithCursor(self):
 		cells = list(self._cells)
 		if self._cursorPos is not None and self._cursorBlinkUp:
 			cells[self._cursorPos] |= self.cursorShape
-		self.display.display(cells)
+
+		try:
+			self.display.display(cells)
+		except:
+			self.handleDisplayUnavailable()
 
 	def _blink(self):
 		self._cursorBlinkUp = not self._cursorBlinkUp
@@ -1474,6 +1478,15 @@ def handleConfigProfileSwitch(self):
 		if display != self.display.name:
 			self.setDisplayByName(display)
 
+	def handleDisplayUnavailable(self):
+		"""Called when the braille display becomes unavailable.
+		This logs an error and disables the display.
+		This is called when displaying cells raises an exception,
+		but drivers can also call it themselves if appropriate.
+		"""
+		log.error("Braille display unavailable. Disabling", exc_info=True)
+		self.setDisplayByName("noBraille", isFallback=True)
+
 def initialize():
 	global handler
 	config.addConfigDirsToPythonPackagePath(brailleDisplayDrivers)