1xx Informational
What it means
The server has received the request headers and the client should proceed to send the request body.
Common causes
Sent automatically by servers supporting HTTP/1.1 when a client includes an "Expect: 100-continue" header before uploading a large body.
How to fix it
Informational only — no action needed. If you never see the actual response after this, check the client's handling of the Expect header.
Frequently asked questions
What does HTTP 100 mean?
The server has received the request headers and the client should proceed to send the request body.
What causes a 100 Continue?
Sent automatically by servers supporting HTTP/1.1 when a client includes an "Expect: 100-continue" header before uploading a large body.
How do I fix a 100 error?
Informational only — no action needed. If you never see the actual response after this, check the client's handling of the Expect header.
Other 1xx Informational codes
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