more fallback

src/Runner.Listener/Configuration/ConfigurationManager.cs

@@ -135,7 +135,8 @@ namespace GitHub.Runner.Listener.Configuration
                     runnerSettings.GitHubUrl = inputUrl;
                     registerToken = await GetRunnerTokenAsync(command, inputUrl, "registration");
                     GitHubAuthResult authResult = await GetTenantCredential(inputUrl, registerToken, Constants.RunnerEvent.Register);
-                    runnerSettings.ServerUrl = authResult.TenantUrl;
+                    var hasLegacyUrl = !string.IsNullOrEmpty(authResult.LegacyUrl);
+                    runnerSettings.ServerUrl = hasLegacyUrl ? authResult.LegacyUrl : authResult.TenantUrl;
                     runnerSettings.UseV2Flow = authResult.UseV2Flow;
                     Trace.Info($"Using V2 flow: {runnerSettings.UseV2Flow}");
                     creds = authResult.ToVssCredentials();

src/Runner.Listener/Configuration/CredentialManager.cs

@@ -96,14 +96,23 @@ namespace GitHub.Runner.Listener.Configuration
         [DataMember(Name = "use_v2_flow")]
         public bool UseV2Flow { get; set; }
 
+        [DataMember(Name = "legacy_url")]
+        public string LegacyUrl { get; set; }
+
+        [DataMember(Name = "legacy_token")]
+        public string LegacyToken { get; set; }
+
         public VssCredentials ToVssCredentials()
         {
             ArgUtil.NotNullOrEmpty(TokenSchema, nameof(TokenSchema));
             ArgUtil.NotNullOrEmpty(Token, nameof(Token));
 
+            var hasLegacyToken = !string.IsNullOrEmpty(LegacyToken);
+            var token = hasLegacyToken ? LegacyToken : Token;
+
             if (string.Equals(TokenSchema, "OAuthAccessToken", StringComparison.OrdinalIgnoreCase))
             {
-                return new VssCredentials(new VssOAuthAccessTokenCredential(Token), CredentialPromptType.DoNotPrompt);
+                return new VssCredentials(new VssOAuthAccessTokenCredential(token), CredentialPromptType.DoNotPrompt);
             }
             else
             {