| 错误信息 | 错误说明 | 
| "upstream prematurely(过早的) closed connection" | 请求uri的时候出现的异常,是由于upstream还未返回应答给用户时用户断掉连接造成的,对系统没有影响,可以忽略 | 
| "recv() failed (104: Connection reset by peer)" | (1)服务器的并发连接数超过了其承载量,服务器会将其中一些连接Down掉; (2)客户关掉了浏览器,而服务器还在给客户端发送数据; (3)浏览器端按了Stop | 
| "(111: Connection refused) while connecting to upstream" | 用户在连接时,若遇到后端upstream挂掉或者不通,会收到该错误 | 
| "(111: Connection refused) while reading response header from upstream" | 用户在连接成功后读取数据时,若遇到后端upstream挂掉或者不通,会收到该错误 | 
| "(111: Connection refused) while sending request to upstream" | Nginx和upstream连接成功后发送数据时,若遇到后端upstream挂掉或者不通,会收到该错误 | 
| "(110: Connection timed out) while connecting to upstream" | nginx连接后面的upstream时超时 | 
| "(110: Connection timed out) while reading upstream" | nginx读取来自upstream的响应时超时 
 | 
| "(110: Connection timed out) while reading response header from upstream" | nginx读取来自upstream的响应头时超时 | 
| "(110: Connection timed out) while reading upstream" | nginx读取来自upstream的响应时超时 | 
| "(104: Connection reset by peer) while connecting to upstream" | upstream发送了RST,将连接重置 | 
| "upstream sent invalid header while reading response header from upstream" | upstream发送的响应头无效 | 
| "upstream sent no valid HTTP/1.0 header while reading response header from upstream" | upstream发送的响应头无效 | 
| "client intended to send too large body" | 用于设置允许接受的客户端请求内容的最大值,默认值是1M,client发送的body超过了设置值 | 
| "reopening logs" | 用户发送kill -USR1命令 | 
| "gracefully shutting down", | 用户发送kill -WINCH命令 | 
| "no servers are inside upstream" | upstream下未配置server | 
| "no live upstreams while connecting to upstream" | upstream下的server全都挂了 | 
| "SSL_do_handshake() failed" | SSL握手失败 | 
| "SSL_write() failed (SSL:) while sending to client" | 
 | 
| "(13: Permission denied) while reading upstream" | 
 | 
| "(98: Address already in use) while connecting to upstream" | 
 | 
| "(99: Cannot assign requested address) while connecting to upstream" | 
 | 
| "ngx_slab_alloc() failed: no memory in SSL session shared cache" | ssl_session_cache大小不够等原因造成 | 
| "could not add new SSL session to the session cache while SSL handshaking" | ssl_session_cache大小不够等原因造成 | 
| "send() failed (111: Connection refused)" | 
原文:http://www.cnblogs.com/wolfshining/p/7998471.html