| Syntax: | fastcgi_next_upstream error | timeout | invalid_header | http_500 | http_503 | http_404 | off ... |
| Default: | error timeout |
| Context: | http server location |
| Reference: | fastcgi_next_upstream |
This directive defines in which cases request will be passed to the next server:
It should be clear that passing request to the next server is possible only if no data have been yet returned to the client. So, if the error or timeout occurred during the data transmission to the client it's too late to fix it.