orbot: obfs3 bridges do not work

Question

I used to be able to connect to the Tor network successfully, but these days It does not work even after I enable bridges (obfs3).

Following, please find the logs:

Orbot ...
tor: PRE: Is binary exec? true
polipo: PRE: Is binary exec? true
obfsclient: PRE: Is binary exec? true
xtables: PRE: Is binary exec? true
Orbot ...
updating torrc custom configuration...
success.
Reading control port config file: /data/data/org.torproject.android/app_bin/control.txt
Connecting to control port: 43547
SUCCESS connected to Tor control port.
Orbot ...
SUCCESS - authenticated to control port.
adding control port event handler
SUCCESS added control port event handler
NOTICE: Opening Socks listener on 127.0.0.1:9050 
Local SOCKS port: 9050
NOTICE: Opening Transparent pf/netfilter listener on 127.0.0.1:9040 
NOTICE: Closing no-longer-configured Transparent pf/netfilter listener on 127.0.0.1:52846 
NOTICE: Closing old Transparent pf/netfilter listener on 127.0.0.1:52846 
Local TransProxy port: 9040
NOTICE: Opening DNS listener on 127.0.0.1:5400 
NOTICE: Closing no-longer-configured DNS listener on 127.0.0.1:59858 
NOTICE: Closing old DNS listener on 127.0.0.1:59858 
Local DNSPort port: 9040
Tor started; process id=9328
updating settings in Tor service
Starting polipo process
SUCCESS - authenticated to control port.
adding control port event handler
SUCCESS added control port event handler
 Tor...
 Tor... 
NOTICE: Delaying directory fetches: No running bridges 
Privoxy ：8118
Polipo process id=9340
NOTICE: Bootstrapped 5%: Connecting to directory server 
NOTICE: Bootstrapped 10%: Finishing handshake with directory server 

Answer 1

It is likely that the bridge you are trying to connect through it to the Tor network is blocked by your ISP. Try to use another bridge. You can get new bridge list from https://bridges.torproject.org/

Answer 2

The problem here was not a bad bridge but a privoxy (proxy) communication issue. There would have been a server-rejection error rather than a socks error if that had been the case.

One larger issue as I see it is that Orbot does not have, and needs to have, a validation routine for addition of bridge lines through its UI to the custom torrc.

I very frequently run into the issue of needing to add fresh bridges, without really knowing which transports will be supported, and whether a list I am trying to paste in has the correct format for line terminations. There are probably other considerations with which I am unfamiliar.

Example: I took a list of three obfs4 bridges obtained moments earlier from torproject by web, and pasted it in. I had to find what appeared to be the end of each line and add a return because it was apparent that terminations had been ignored. I exited and restarted orbot. It would not connect, and offered no useful errors, other than a note indicating custom torrc is invalid.