Windows平台C#程序突发无法连接Firestore问题求助

此前Windows（.NET Framework 4.7.2）、Android和iOS（.NET MAUI 7.0）端应用均可正常连接Firestore。昨日起无任何代码变更，但Windows端突然无法连接，抛出如下错误：

Exception thrown: 'Grpc.Core.RpcException' in mscorlib.dll
Grpc.Core.RpcException: Status(StatusCode="Unavailable", Detail="failed to connect to all addresses", DebugException="Grpc.Core.Internal.CoreErrorDetailException: {"created":"@1689930000.542000000","description":"Failed to pick subchannel","file":"..\\..\\..\\src\\core\\ext\\filters\\client_channel\\client_channel.cc","file_line":3218,"referenced_errors":[{"created":"@1689930000.542000000","description":"failed to connect to all addresses","file":"..\\..\\..\\src\\core\\lib\\transport\\error_utils.cc","file_line":165,"grpc_status":14}]}")
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Google.Api.Gax.Grpc.ApiCallRetryExtensions.<>c__DisplayClass0_0`2.<<WithRetry>b__0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Google.Cloud.Firestore.WriteBatch.<CommitAsync>d__15.MoveNext() in /_/apis/Google.Cloud.Firestore/Google.Cloud.Firestore/WriteBatch.cs:line 226
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Google.Cloud.Firestore.DocumentReference.<CreateAsync>d__19.MoveNext() in /_/apis/Google.Cloud.Firestore/Google.Cloud.Firestore/DocumentReference.cs:line 106
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Google.Cloud.Firestore.CollectionReference.<AddAsync>d__12.MoveNext() in /_/apis/Google.Cloud.Firestore/Google.Cloud.Firestore/CollectionReference.cs:line 94
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at WindowsEnviromentTestDigitalForm.Form1.<btnInsertFix_Click>d__3.MoveNext()

连接代码如下：

string path = AppDomain.CurrentDomain.BaseDirectory + @"privatykey.json";
Environment.SetEnvironmentVariable("GOOGLE_APPLICATION_CREDENTIALS", path);

FirestoreDb databaseFS = FirestoreDb.Create("appname");

CollectionReference collectionReference = databaseFS.Collection("Collection_Name");
Dictionary<string, object> map = new Dictionary<string, object>() 
{
      {"Test1", 0}, {"Test2", 1}, {"Test3", 3}
};

collectionReference.AddAsync(map);

可能原因及解决方法 #

1. Windows系统网络环境变化 #

• 防火墙/杀毒软件拦截：Windows防火墙或第三方杀毒软件可能更新规则，拦截了Grpc通信端口（Firestore默认用443端口，但HTTP/2多路复用可能被误判）。
  • 解决：将应用加入防火墙白名单，临时关闭杀毒软件测试；检查Windows Defender的应用控制规则。
• 代理配置变更：系统代理、VPN设置被修改，导致Grpc无法解析Firestore地址。
  • 解决：检查代理设置，确保可正常访问firestore.googleapis.com；关闭代理后测试连接。

2. Grpc依赖兼容性问题 #

• NuGet包版本冲突：.NET Framework 4.7.2下的Grpc.Core、Google.Cloud.Firestore可能存在隐性版本变更（自动还原时更新），与MAUI端版本不一致。
  • 解决：锁定与MAUI端一致的NuGet包版本，清理缓存后重新安装依赖。
• HTTP/2支持缺陷：.NET Framework对HTTP/2的支持不完善，导致连接失败。
  • 解决：强制Grpc使用HTTP/1.1，修改初始化代码：

    var channel = new Grpc.Core.Channel("firestore.googleapis.com:443", Grpc.Core.ChannelCredentials.SecureSsl, new[]
    {
        new Grpc.Core.ChannelOption(Grpc.Core.ChannelOptions.HttpProtocolVersion, Grpc.Core.HttpProtocolVersion.Http1)
    });
    var client = new Google.Cloud.Firestore.V1.Firestore.FirestoreClient(channel);
    FirestoreDb databaseFS = FirestoreDb.Create("appname", client);
    

3. 服务账号密钥问题 #

• 文件权限丢失：Windows下应用运行用户失去privatykey.json的读取权限（文件移至受保护目录或权限被修改）。
  • 解决：检查密钥文件的读取权限，将文件移至明确路径（如C:\temp）后修改代码路径测试。
• 密钥失效：服务账号密钥在Google Cloud Console被撤销，Windows端缓存凭证失效（移动端缓存未过期）。
  • 解决：登录Google Cloud Console检查密钥状态，重新生成密钥文件替换旧文件。

4. 临时网络或服务端问题 #

• 局部网络波动：Windows所在网络出现DNS解析失败、丢包，导致Grpc无法连接。
  • 解决：更换网络（如手机热点）测试；运行nslookup firestore.googleapis.com检查DNS解析，telnet firestore.googleapis.com 443测试端口连通性。
• Google服务局部故障：Windows端连接的Firestore节点临时故障。
  • 解决：确认Google Cloud服务状态，等待一段时间后重试。

内容的提问来源于stack exchange，提问作者WhyAlfred