[Solved] Developing offline

[Jay Avery]

This weekend I'm going to be travelling and I'd like to be able to bring my laptop and work on my mod. But I just experimented with turning off my internet and then trying to run my mod from eclipse, and I got a crash:

 

 

[14:48:21] [main/INFO]: Logging in with username & password
[14:48:23] [main/ERROR] [GradleStart]: -- Login failed!  Cannot contact authentication server
Exception in thread "main" java.lang.RuntimeException: com.mojang.authlib.exceptions.AuthenticationUnavailableException: Cannot contact authentication server
at com.google.common.base.Throwables.propagate(Throwables.java:160)
at GradleStart.attemptLogin(GradleStart.java:103)
at GradleStart.preLaunch(GradleStart.java:59)
at net.minecraftforge.gradle.GradleStartCommon.launch(GradleStartCommon.java:81)
at GradleStart.main(GradleStart.java:26)
Caused by: com.mojang.authlib.exceptions.AuthenticationUnavailableException: Cannot contact authentication server
at com.mojang.authlib.yggdrasil.YggdrasilAuthenticationService.makeRequest(YggdrasilAuthenticationService.java:85)
at com.mojang.authlib.yggdrasil.YggdrasilUserAuthentication.logInWithPassword(YggdrasilUserAuthentication.java:78)
at com.mojang.authlib.yggdrasil.YggdrasilUserAuthentication.logIn(YggdrasilUserAuthentication.java:61)
at GradleStart.attemptLogin(GradleStart.java:98)
... 3 more
Caused by: java.net.UnknownHostException: authserver.mojang.com
at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at sun.security.ssl.SSLSocketImpl.connect(Unknown Source)
at sun.net.NetworkClient.doConnect(Unknown Source)
at sun.net.www.http.HttpClient.openServer(Unknown Source)
at sun.net.www.http.HttpClient.openServer(Unknown Source)
at sun.net.www.protocol.https.HttpsClient.<init>(Unknown Source)
at sun.net.www.protocol.https.HttpsClient.New(Unknown Source)
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(Unknown Source)
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getOutputStream0(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(Unknown Source)
at sun.net.www.protocol.https.HttpsURLConnectionImpl.getOutputStream(Unknown Source)
at com.mojang.authlib.HttpAuthenticationService.performPostRequest(HttpAuthenticationService.java:77)
at com.mojang.authlib.yggdrasil.YggdrasilAuthenticationService.makeRequest(YggdrasilAuthenticationService.java:66)
... 6 more

 

 

Is there a setting I can change to allow me to run Forge while not connected to the internet? Surely it is possible, since you can play vanilla Minecraft offline?

[larsgerrits]

(I think) Minecraft in a dev environment only tries to connect to the authentication server if there's both a username (email) and password available from the program arguments. If you have them, you might want to check if removing those fixes the issue.

[Jay Avery]

Oh, thanks for the tip - that's done it! I just removed my username from the run configuration arguments and it ran offline with no problems.