Reported by briang1 on 2013-07-01 12:03
Installation of an older copy of the nvda installer over a current one fails with no speech if nvda is selected in the installed snap before loading the earlier installer.
In the case of release versions, where errors are suppressed it changes the synth to silence and gives no clues as to what is going on, but using a last known bad snapshot you get the following log when you boot a working copy back in again.
nvda_snapshot_main-5967.exe
gives the error, while...
nvda_snapshot_main-5973.exe does not and works correctly.

The error is
INFO - synthDrivers.espeak.SynthDriver.init (12:24:03):
Using eSpeak version 1.46.02 06.Jan.12
WARNING - synthDriverHandler.SynthDriver.loadSettings (12:24:03):
No such voice: en
ERROR - synthDriverHandler.setSynth (12:24:03):
setSynth
Traceback (most recent call last):
File "synthDriverHandler.pyc", line 80, in setSynth
File "synthDriverHandler.pyc", line 453, in loadSettings
File "synthDriverHandler.pyc", line 28, in changeVoice
File "synthDrivers\espeak.pyc", line 153, in _set_voice
File "synthDriverHandler.pyc", line 321, in _get_language
KeyError: u'en'
DEBUG - speechDictHandler.SpeechDict.load (12:24:03):
Loading speech dictionary 'C:\Documents and Settings\brian\Application Data\nvda\speechDicts\silence.dic'...
DEBUG - speechDictHandler.SpeechDict.load (12:24:03):
file 'C:\Documents and Settings\brian\Application Data\nvda\speechDicts\silence.dic' not found.
INFO - synthDriverHandler.setSynth (12:24:03):
Loaded synthDriver silence

Now as this has obviously looked at the .ini file and found something it did not understand, maybe it just assumes its not available. Obviously, one cannot change something written back in time, but maybe people could be warned somehow that its a bad idea to do this!

I also think that the save on exit should not be honoured in the installer itself, as this alters the .ini file and thus screws it up permanently to silence in this case on the last release version 2012.3.1. The snapshots are now fine in this regard. IE attempting to reload 2012.3.1, will end in silence on the installed copy even if you back out of the installer or whatever. Best advice is to use a different synth before you attempt to load an old version, as this usually works.
However even if you do do this, afterwards any attempt to select
espeak will fail of course. One would presumably need to completely uninstall the later version before installing the older one.

I did this test as a couple of people attempted this downdate, and found it silent.