首次访问Status显示：(failed) net::ERR_HTTP2_PROTOCOL_ERROR, 页面也没有正常展示

[dean-shanghai]

首次访问Status显示：(failed) net::ERR_HTTP2_PROTOCOL_ERROR, 页面也没有正常展示，如图：

[toolgood]

ERR_HTTP2_PROTOCOL_ERROR 是一个Chrome浏览器中的错误，表明浏览器在使用HTTP/2协议时遇到了协议违规的情况。这可能是由于服务器发送了不符合HTTP/2标准的响应导致的。

[toolgood]

我更新到.net 8，没有重现这个问题

[dean-shanghai]

报错情况只在首次访问页面时出现（首次访问页面：html文件夹中还没有生成该页面的.html/.gzip/.br等缓存文件）。

报错信息：System.InvalidOperationException: Headers are read-only, response has already started.

fail: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[1]
An unhandled exception has occurred while executing the request.
System.InvalidOperationException: Headers are read-only, response has already started.
at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpHeaders.ThrowHeadersReadOnlyException()
at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpHeaders.Microsoft.AspNetCore.Http.IHeaderDictionary.set_Item(String key, StringValues value)
at Microsoft.AspNetCore.Mvc.HtmlStaticFileAttribute.OnResultExecutionAsync(ResultExecutingContext context, ResultExecutionDelegate next) in C:...\Attributes\HtmlStaticFileAttribute.cs:line

报错的位置是这一句：context.HttpContext.Response.Headers["Cache-Control"] = "max-age=" + (CurrPageExpireMinutes ?? ExpireMinutes) * 60;

[toolgood]

修改好了，添加了一个判断

                if (context.HttpContext.Response.Headers.IsReadOnly == false) {
                    var fi = new FileInfo(filePath);
                    var etag = fi.LastWriteTimeUtc.Ticks.ToString();
                    context.HttpContext.Response.Headers["Cache-Control"] = "max-age=" + (CurrPageExpireMinutes ?? ExpireMinutes) * 60;
                    context.HttpContext.Response.Headers["Etag"] = etag;
                    context.HttpContext.Response.Headers["Date"] = DateTime.Now.ToString("r");
                    context.HttpContext.Response.Headers["Expires"] = DateTime.Now.AddMinutes(CurrPageExpireMinutes ?? ExpireMinutes).ToString("r");
                }