diff --git a/ShadowsocksX-NG2/Domain/ProxySettingsFileStore.swift b/ShadowsocksX-NG2/Domain/ProxySettingsFileStore.swift
index f2c495a4..52697238 100644
--- a/ShadowsocksX-NG2/Domain/ProxySettingsFileStore.swift
+++ b/ShadowsocksX-NG2/Domain/ProxySettingsFileStore.swift
@@ -224,8 +224,15 @@ private struct ProxySettingsRecord: Codable, Equatable, Sendable {
     proxyExceptions =
       try container.decodeIfPresent(String.self, forKey: .proxyExceptions)
       ?? ProxySettings.defaultProxyExceptions
-    preferredMode =
-      try container.decodeIfPresent(ProxyModeKind.self, forKey: .preferredMode) ?? .rule
+    // 旧 NG2 偏好里的 "pac" 等已删除值容错回落到规则模式（issue #67：
+    // 未发布的 PAC 偏好不做迁移，但解码失败会把全部保留字段连坐丢掉）。
+    if let rawMode = try container.decodeIfPresent(String.self, forKey: .preferredMode),
+      let mode = ProxyModeKind(rawValue: rawMode)
+    {
+      preferredMode = mode
+    } else {
+      preferredMode = .rule
+    }
     // 规则模式子选项（issue #63）：出厂「未匹配时代理」。
     ruleDefaultAction =
       try container.decodeIfPresent(RuleDefaultAction.self, forKey: .ruleDefaultAction)
diff --git a/ShadowsocksX-NG2/Tests/ProxySettingsFileStoreTests.swift b/ShadowsocksX-NG2/Tests/ProxySettingsFileStoreTests.swift
index 35855c85..59c83090 100644
--- a/ShadowsocksX-NG2/Tests/ProxySettingsFileStoreTests.swift
+++ b/ShadowsocksX-NG2/Tests/ProxySettingsFileStoreTests.swift
@@ -82,6 +82,20 @@ final class ProxySettingsFileStoreTests: XCTestCase {
     XCTAssertFalse(raw.contains("enabledModes"))
   }
 
+  func testLegacyPACPreferredModeFallsBackToRuleWithoutLosingOtherFields() throws {
+    try writeRaw(
+      """
+      {"preferredMode":"pac","socksPort":2086,"httpPort":2087,"timeoutSeconds":120,
+       "pacUserRules":"@@example.com","gfwListURLConfigured":true,"pacPort":2089}
+      """)
+
+    let loaded = try store.load()
+    XCTAssertEqual(loaded.preferredMode, .rule)
+    XCTAssertEqual(loaded.listen.socksPort, 2086)
+    XCTAssertEqual(loaded.listen.httpPort, 2087)
+    XCTAssertEqual(loaded.timeoutSeconds, 120)
+  }
+
   func testInvalidSaveDoesNotTouchExistingSettings() throws {
     try store.save(ProxySettings())
     var invalid = ProxySettings()