Undertow write-timeout can cause closing a connection for a long-polling request without sending the last zero-length chunk like 0\r\n\r\n. This behavior causes a browser-side error, e.g. net::ERR_INCOMPLETE_CHUNKED_ENCODING in Google Chrome.

In current Undertow implementation of write-timeout, for requests that re-use a keep-alive connection, the write-timeout set during the previous request processing is taken over to the next request. As a result, a zero chunk truncated response is returned if meet the following conditions are true:

• The request re-use a keep-alive connection.
• The request takes longer than write-timeout like long-polling processing by AsyncServlet.
• Transfer-Encoding: chunked is applied to the response by calling flush() in the servlet.

Even if the write-timeout is reached, it is expected to write the last chunk to the socket before closing a connection.