> Yes I know,
> but it's very strange situation that can't understand. Code is the same,
> nothing is changed. Only nginx version and http2 support on host.

nginx 1.9.5 has a bug (#800): $server_protocol is empty on HTTP2.
This is fixed in nginx 1.9.6, so with 1.9.6 PHP/FCGI for
the first time sees HTTP/2.0 as SERVER_PROTOCOL.

You can probably reproduce the problem in 1.9.5 if set it manually:
fastcgi_param  SERVER_PROTOCOL    HTTP/2.0;

Or workaround it in 1.9.6 if reset:
fastcgi_param  SERVER_PROTOCOL    HTTP/1.1;


In the end, you have to fix your PHP code.
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