Internet Information Services
Microsoft web server software.
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IIS php fastcgi and chunked request body
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Jan Vávra
386
Reputation points
I've found out IIS doesn't support a chunked request bodies, eg.
I found a mention:
In HTTP/1.1, chunked transfer encoding is primarily a server-side response mechanism. The specification (RFC 9112, previously RFC 7230 and RFC 2616) defines chunked encoding as a way for the server to send responses when the content length is unknown in advance.
However, HTTP/1.1 does allow chunked requests, but support for them is optional for servers. Many web servers, including IIS, do not support chunked request bodies, meaning they do not accept incoming requests that use chunked transfer encoding.
Anyway. In my scenario the curl never returns and still blocks a IIS/php-cgi.exe process. On a second request it starts second php fastcgi php-cgi.exe process untill a maximum configured (eg. 16).
In that case everything is blocked and no other clients like browser are served by php-cgi.
Still I can get a static content but the php application is stucked.
Why IIS doesn't respond something like HTTP 400 Bad Request etc. ?
Can I still configure IIS to accept chunked request bodies?
Jan.
{count} votes
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Lex Li (Microsoft) 6,032 Reputation points Microsoft Employee2025-03-18T22:02:00.13+00:00 There are quite a few similar issues related to IIS chunked support. (You might want to read posts like this and etc.) In short, to investigate/resolve such issues, the guy will need both IIS/PHP knowledge, which isn't an easy task. But Microsoft no more supports PHP on IIS/Windows, https://docs.lextudio.com/phpmanager/getting-started/supported-platforms#php-on-windows-status So your first option is maybe to move to Linux where there is a stronger PHP community.
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XuDong Peng-MSFT 11,891 Reputation points Microsoft External Staff2025-03-19T09:01:20.2566667+00:00 Hi @Jan Vávra,
Can I still configure IIS to accept chunked request bodies?
As mentioned in your problem description, this encoding format is used to send the response, not to parse the request body. You may need to understand how chunking works and implement this requirement through logic code.
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Jan Vávra 386 Reputation points
2025-03-19T09:51:05.7233333+00:00 Definitely it is a client request, see the curl command.
And this can even cause a Denial of Service. All fastcgi php-cgi.exe processes become stucked and no other php pages are served until a fastcgi timeout occurs.
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