当前系统环境：centos7 x64. dotnet 2.0.
不管是
ServicePointManager.ServerCertificateValidationCallback = (a, b, c, d) => true;
还是：
HttpClient httpClient = new HttpClient(new HttpClientHandler() { ServerCertificateCustomValidationCallback = (a, b, c, d) => true });
都会发生错误：
错误信息大致如下：
(The handler does not support custom handling of certificates with this combination of libcurl (7.29.0) and its SSL backend ("NSS/3.28.4").) ---> System.PlatformNotSupportedException: The handler does not support custom handling of certificates with this combination of libcurl (7.29.0) and its SSL backend ("NSS/3.28.4").
at System.Net.Http.CurlHandler.SslProvider.SetSslOptionsForUnsupportedBackend(EasyRequest easy, ClientCertificateProvider certProvider)
at System.Net.Http.CurlHandler.SslProvider.SetSslOptions(EasyRequest easy, ClientCertificateOption clientCertOption)
解决方案：
# yum update（可选）# yum install openssl-devel gcc #安装openssl和gcc# 安装指定版本的curl# wget https://curl.haxx.se/download/curl-7.55.1.tar.gz# tar -zxf curl-7.55.1.tar.gz# cd curl-7.55.1# ./configure --prefix=/usr/local/curl/ --without-nss --with-ssl=/usr/local/ssl/# make# make install#备份原来的curlmv /usr/bin/curl /usr/bin/curl.bak#将安装的curl 创建软连ln -s /usr/local/curl/bin/curl /usr/bin/curl# ?curl --version#差不多输出下面的内容#curl 7.55.1 (x86_64-pc-linux-gnu) libcurl/7.55.1 OpenSSL/1.0.2k zlib/1.2.7#增加lib搜索目录# vi /etc/ld.so.conf #增加# /usr/local/curl/lib# cat /etc/ld.so.conf 差不多下面这样子#include ld.so.conf.d/*.conf/usr/local/curl/lib# 重新load配置# ldconfig参考文章：
https://www.latoooo.com/xia_zhe_teng/368.htm
https://segmentfault.com/a/1190000012282935
https://www.cnblogs.com/Anker/p/3209876.html
https://github.com/dotnet/corefx/issues/9728#issuecomment-286251370