215631 2020-08-18 16:47:27 -0700 Webkit incorrectly reuses closed tcp connections: Failed to load resource: The network connection was lost. 2025-11-19 16:52:14 -0800 1 1 1 Unclassified WebKit WebCore JavaScript Safari 13 Mac macOS 10.15 NEW InRadar P2 Critical --- 1 kevmun webkit-unassigned ap joseph.belmonte webkit-bug-importer youennf oldest_to_newest 1681242 0 kevmun 2020-08-18 16:47:27 -0700 In our webapp using webkit, we see an issue with certain AJAX requests, "Failed to load resource: The network connection was lost." We have observed that using Fetch (https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API) we hit a timing issue where the browser tries to reuse a connection that was recently closed. With optimal network conditions, it’s about a 2% chance of this occurring. With high latency packets, we can reproduce %15 of the time. Steps to repro: Navigate at exactly 7 seconds (when our server terminates the connection, reproducing outside this environment will depend on the server timeouts). We've observed our TCP connections to be in TIME_WAIT at the time of failure; The docs here refer to webkit keeping connections open https://developer.apple.com/library/archive/documentation/NetworkingInternetWeb/Conceptual/NetworkingOverview/CommonPitfalls/CommonPitfalls.html 1681303 1 webkit-bug-importer 2020-08-19 00:50:06 -0700 <rdar://problem/67385261> 1681500 2 ap 2020-08-19 15:30:11 -0700 > Navigate at exactly 7 seconds (when our server terminates the connection, reproducing outside this environment will depend on the server timeouts). Can you share the server URL? 1684235 3 ap 2020-08-31 13:36:47 -0700 As a workaround, can you use HTTP/2 instead instead of HTTP/1 or add `Keep-Alive: timeout=7` header?