ErrorCode

Invalid argument passed.

Out of buffer space.

The specified protocol version is not supported.

Used as a return value from http2_send_callback and http2_recv_callback to indicate that the operation would block.

General protocol error

The frame is invalid.

The peer performed a shutdown on the connection.

Used as a return value from DataProvider to indicate that data transfer is postponed. See DataProvider for details.

Stream ID has reached the maximum value. Therefore no stream ID is available.

The stream is already closed; or the stream ID is invalid.

RST_STREAM has been added to the outbound queue. The stream is in closing state.

The transmission is not allowed for this stream (e.g., a frame with END_STREAM flag set has already sent).

The stream ID is invalid.

The state of the stream is not valid (e.g., DATA cannot be sent to the stream if response HEADERS has not been sent).

Another DATA frame has already been deferred.

Starting new stream is not allowed (e.g., GOAWAY has been sent and/or received).

GOAWAY has already been sent.

The received frame contains the invalid header block (e.g., There are duplicate header names; or the header names are not encoded in US-ASCII character set and not lower cased; or the header name is zero-length string; or the header value contains multiple in-sequence NUL bytes).

Indicates that the context is not suitable to perform the requested operation.

The user callback function failed due to the temporal error.

The length of the frame is invalid, either too large or too small.

Header block inflate/deflate error.

Flow control error

Insufficient buffer size given to function.

Callback was paused by the application

There are too many in-flight SETTING frame and no more transmission of SETTINGS is allowed.

The server push is disabled.

DATA frame for a given stream has been already submitted and has not been fully processed yet.

The current session is closing due to a connection error or http2_session_terminate_session() is called.

Invalid HTTP header field was received and stream is going to be closed.

The errors < FATAL mean that the library is under unexpected condition and processing was terminated (e.g., out of memory). If application receives this error code, it must stop using that Session object and only allowed operation for that object is deallocate it using http2_session_del().

Out of memory. This is a fatal error.

The user callback function failed. This is a fatal error.

Invalid connection preface was received and further processing is not possible.