The following warning message is output by NGINX being used as a reverse proxy.

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 while reading upstream, client: 1.1.1.1, server: abc.com, request:: warning 24547 # 0: * 2408454 an upstream response is buffered to a temporary file / var / cache / nginx / proxy_temp / 5/31/0000017695 while reading upstream, GET
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Question
· While checking other cases in the forum, this message shows that the response from the upstream is not cached in the buffer but cached on the disk, but is the buffer subject only to the header or Is it the entire response?

· When this message is output, is the communication itself continued?

· Please tell me how to suppress output of this message and how to deal with it.

· Which function corresponds to the function outputted by this message?
(Proxy_buffer_size, proxy_buffers, is it another function?)