JeffreySu/WeiXinMPSDK · error · ArgumentNullException

fileStream

Error message

fileStream

What it means

RequestMultipartCoreAsync is the shared implementation behind the four public multipart upload methods (RequestMultipartAsync and its with-max-size / file-digest / filename-and-digest variants). It validates the fileStream argument and throws ArgumentNullException when the uploaded content stream is null, because a multipart file upload cannot be constructed without stream content to write into the multipart body. The offending input is the fileStream parameter passed by one of the public wrappers.

Solutions

1. Open the file stream before the call and assert it is non-null and readable (stream.CanRead)
2. Check the file exists with File.Exists before opening to give a better error
3. Ensure the stream is not disposed/closed before the async upload completes

Example fix

// before
using FileStream fs = fileExists ? File.OpenRead(path) : null;
await apiRequest.RequestMultipartAsync(url, fileName, fs);
// after
if (!File.Exists(path)) throw new FileNotFoundException(path);
using var fs = File.OpenRead(path);
await apiRequest.RequestMultipartAsync(url, fileName, fs);

if (fileStream == null || !fileStream.CanRead)
    throw new InvalidOperationException("文件流不可读，请先打开文件");

try { await apiRequest.RequestMultipartAsync(url, fileName, fileStream); }
catch (ArgumentNullException ex) when (ex.ParamName == "fileStream") { log.Error("文件流为空", ex); throw; }

When it happens

Trigger: Passing a null Stream — commonly File.OpenRead on a nonexistent path assigned before the call and swallowed, or a stream from an async open that returned null.

Common situations: File missing at runtime (wrong working directory), stream already disposed and nulled, or conditional file-open logic that skipped opening.

Related errors

• tenPayV3Info 参数不能为空！
• brandApiCredentials
• data 不能为 null！
• 文件名不能为空。
• buttonGroupBase不可以为空！

AI-assisted analysis of JeffreySu/WeiXinMPSDK@be573f6f94 (2026-09-12). Data as JSON: /api/errors/4e8a4fbef15a4fdb. Report an issue: GitHub.

Appendix: source

Thrown at src/Senparc.Weixin.TenPay/Senparc.Weixin.TenPayV3/HttpHandlers/TenPayApiRequest.cs:381

        {
            return RequestMultipartCoreAsync(url, fileName, fileStream,
                cancellationToken,
                MultipartMetaFieldStyle.FilenameAndFileDigest, timeOut,
                checkSign, createDefaultInstance, maxFileBytes);
        }

        private async Task<T> RequestMultipartCoreAsync<T>(string url, string fileName,
            Stream fileStream, CancellationToken cancellationToken,
            MultipartMetaFieldStyle metaFieldStyle, int timeOut, bool checkSign,
            Func<T> createDefaultInstance, int? maxFileBytes = null)
            where T : ReturnJsonBase, new()
        {
            if (string.IsNullOrWhiteSpace(fileName))
            {
                throw new ArgumentException("文件名不能为空。", nameof(fileName));
            }

            _ = fileStream ?? throw new ArgumentNullException(nameof(fileStream));
            if (timeOut <= 0 && timeOut != Timeout.Infinite)
            {
                throw new ArgumentOutOfRangeException(nameof(timeOut), "超时时间必须大于 0，或使用 Timeout.Infinite。 ");
            }
            if (maxFileBytes.HasValue && maxFileBytes.Value <= 0)
            {
                throw new ArgumentOutOfRangeException(nameof(maxFileBytes),
                    "文件大小上限必须大于 0。");
            }
            if (maxFileBytes.HasValue && fileStream.CanSeek &&
                fileStream.Length - fileStream.Position > maxFileBytes.Value)
            {
                throw new InvalidDataException(
                    $"上传文件超过允许上限 {maxFileBytes.Value} 字节。");
            }

            T result = null;
            try

View on GitHub (pinned to be573f6f94)