这是一个很晚的答案，但我遇到了类似的问题，我想我发现了问题是什么：您为长轮询设置了20秒的WaitTimeSeconds（这是一个好主意），但是HTTP客户机超时的时间比这要早。
WaitTimeSeconds的文档说明：

// To avoid HTTP errors, ensure that the HTTP response timeout for ReceiveMessage
// requests is longer than the WaitTimeSeconds parameter. For example, with
// the Java SDK, you can set HTTP transport settings using the NettyNioAsyncHttpClient
// (https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/http/nio/netty/NettyNioAsyncHttpClient.html)
// for asynchronous clients, or the ApacheHttpClient (https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/http/apache/ApacheHttpClient.html)
// for synchronous clients.

至少，从v1.44.39到aws-sdk-go。
下一页介绍了如何配置自定义HTTP客户机：https://docs.aws.amazon.com/sdk-for-go/v1/developer-guide/custom-http.html
我将把该页的所有代码复制到这里，以供后人使用：

type HTTPClientSettings struct {
    Connect          time.Duration
    ConnKeepAlive    time.Duration
    ExpectContinue   time.Duration
    IdleConn         time.Duration
    MaxAllIdleConns  int
    MaxHostIdleConns int
    ResponseHeader   time.Duration
    TLSHandshake     time.Duration
}

func NewHTTPClientWithSettings(httpSettings HTTPClientSettings) (*http.Client, error) {
    var client http.Client
    tr := &http.Transport{
        ResponseHeaderTimeout: httpSettings.ResponseHeader,
        Proxy:                 http.ProxyFromEnvironment,
        DialContext: (&net.Dialer{
            KeepAlive: httpSettings.ConnKeepAlive,
            DualStack: true,
            Timeout:   httpSettings.Connect,
        }).DialContext,
        MaxIdleConns:          httpSettings.MaxAllIdleConns,
        IdleConnTimeout:       httpSettings.IdleConn,
        TLSHandshakeTimeout:   httpSettings.TLSHandshake,
        MaxIdleConnsPerHost:   httpSettings.MaxHostIdleConns,
        ExpectContinueTimeout: httpSettings.ExpectContinue,
    }

    // So client makes HTTP/2 requests
    err := http2.ConfigureTransport(tr)
    if err != nil {
        return &client, err
    }

    return &http.Client{
        Transport: tr,
    }, nil
}

httpClient, err := NewHTTPClientWithSettings(HTTPClientSettings{
    Connect:          5 * time.Second,
    ExpectContinue:   1 * time.Second,
    IdleConn:         90 * time.Second,
    ConnKeepAlive:    30 * time.Second,
    MaxAllIdleConns:  100,
    MaxHostIdleConns: 10,
    ResponseHeader:   5 * time.Second,
    TLSHandshake:     5 * time.Second,
})
if err != nil {
    fmt.Println("Got an error creating custom HTTP client:")
    fmt.Println(err)
    return
}

sess := session.Must(session.NewSession(&aws.Config{
    HTTPClient: httpClient,
}))

sqsClient := sqs.New(sess)

您将需要配置超时设置。特别是，我将Connect、TLSHandshake和ResponseHeader设置为25秒，不再收到任何错误。