I am unable to set-up Sauce Connect using v4 and logs are also not created automatically. I always get timeout exception "Time out while waiting for Sauce Connect to start, please check the Sauce Connect log". Since logs are not created, I am unable to know reason for failure. Although I have enabled verbose logging but reason for failure is not known. But I can successfully execute my tests using Sauce Connect v3 and logs are also automatically created. I am attaching Jenkins console output for v4 and v3.

Sauce Connect using v4(Jenkins Console):
Starting Sauce Connect on master node using identifier: my-tun2
Launching Sauce Connect on Akash
30 May 11:31:58 - Error opening sc_my-tun2.log: No such file or directory
Time out while waiting for Sauce Connect to start, please check the Sauce Connect log
Flushing Sauce Connect Input Stream
Flushing Sauce Connect Error Stream
Closing Sauce Connect process
FATAL: Time out while waiting for Sauce Connect to start, please check the Sauce Connect log
com.saucelabs.ci.sauceconnect.AbstractSauceTunnelManager$SauceConnectDidNotStartException: Time out while waiting for Sauce Connect to start, please check the Sauce Connect log
at com.saucelabs.ci.sauceconnect.AbstractSauceTunnelManager.openConnection(AbstractSauceTunnelManager.java:337)
at hudson.plugins.sauce_ondemand.SauceOnDemandBuildWrapper$SauceConnectHandler.call(SauceOnDemandBuildWrapper.java:824)
at hudson.plugins.sauce_ondemand.SauceOnDemandBuildWrapper.setUp(SauceOnDemandBuildWrapper.java:279)
at hudson.model.Build$BuildExecution.doRun(Build.java:156)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:537)
at hudson.model.Run.execute(Run.java:1744)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
at hudson.model.ResourceController.execute(ResourceController.java:98)
at hudson.model.Executor.run(Executor.java:374)

Sauce Connect using v3(Jenkins Console):
Starting Sauce Connect on master node using identifier: my-tun2
Launching Sauce Connect on Akash

• • • Support for Sauce Connect v3 is scheduled to end on 19 August 2015 ***
    • Please update your settings to use Sauce Connect v4 ***
      Sauce Connect 3.1-r32, build 50
• Debug messages will be sent to sauce_connect.log
  2015-05-30 12:26:28.124:INFO::jetty-7.x.y-SNAPSHOT
  2015-05-30 12:26:29.791:INFO::Started SelectChannelConnector@0.0.0.0:60743
  .---------------------------------------------------.

  Have questions or need help with Sauce Connect?

  Contact us: http://support.saucelabs.com/forums

  Terms of Service: http://saucelabs.com/tos

  -----------------------------------------------------
  2015-05-30 12:26:30,638 - / Starting \
  2015-05-30 12:26:30,733 - Please wait for "You may start your tests" to start your tests.
  2015-05-30 12:26:30,766 - Forwarding: None:['80'] -> 127.0.0.1:['60743']
  2015-05-30 12:26:30,911 - Succesfully connected to local server 127.0.0.1:60743 in 133ms
  2015-05-30 12:26:32,453 -

  Unknown macro: {"tunnel_identifier"}

  2015-05-30 12:26:37,595 - Tunnel remote VM is provisioned (0257bb33cf9d4e5585b909630c5ecbe0)
  2015-05-30 12:26:39,104 - Tunnel remote VM is booting ..
  2015-05-30 12:26:45,944 - Tunnel remote VM is running at maki79134.miso.saucelabs.com
  2015-05-30 12:26:46,045 - Succesfully connected to local server 127.0.0.1:60743 in 0ms
  2015-05-30 12:26:46,056 - Starting connection to tunnel host...
  2015-05-30 12:26:46,061 - Connecting to tunnel host maki79134.miso.saucelabs.com as akashbhardwaj
  2015-05-30 12:26:46,778 - Forwarding Selenium with ephemeral port 60749
  2015-05-30 12:26:46.782:INFO::jetty-7.x.y-SNAPSHOT
  2015-05-30 12:26:46.794:INFO::Started SelectChannelConnector@0.0.0.0:4445
  2015-05-30 12:26:46,798 - Selenium HTTP proxy listening on port 4445
  2015-05-30 12:26:48,270 - Successful handshake with Sauce Connect server
  2015-05-30 12:26:48,318 - Tunnel host version: 0.1.0, remote endpoint ID: af51f4769e524692827af6d81f6099de
  2015-05-30 12:26:48,321 - Connected! You may start your tests.
  Sauce Connect 3.1.26 now launched for: my-tun2
  Incremented process count for my-tun2, now 1

Can you resolve this ASAP as SauceLabs are going to deprecate Sauce Connect v3 soon..