I see this a lot in our test runs and it might be causing Bug 1687739.

08-04 03:54:50.534  3553  3569 E GeckoConsole: [JavaScript Error: "NS_ERROR_FILE_NOT_FOUND: " {file: "resource://gre/modules/SessionStoreFunctions.jsm" line: 120}]
08-04 03:54:50.534  3553  3569 E GeckoConsole: SSF_updateSessionStoreForWindow@resource://gre/modules/SessionStoreFunctions.jsm:120:5
08-04 03:54:50.534  3553  3569 E GeckoConsole: UpdateSessionStoreForStorage@resource://gre/modules/SessionStoreFunctions.jsm:54:35
08-04 03:54:50.534  3553  3569 E GeckoConsole: handleNewSession@resource://gre/modules/GeckoViewNavigation.jsm:355:17
08-04 03:54:50.534  3553  3569 E GeckoConsole: createContentWindowInFrame@resource://gre/modules/GeckoViewNavigation.jsm:425:26

farre is on PTO, nika do you have ideas here?

fwiw, the workaround we use for b2g is https://github.com/kaiostech/gecko-b2g/commit/a358ec6da255045562b50980e8c2fbf79089b4ac

Sorry about this, it fails because it tries to load SessionStore.jsm. I'm fixing this in bug 1722485.

Out of curiosity, where does GeckoView collect/restore session storage?

Kashav: right now we do it in https://searchfox.org/mozilla-central/rev/4b49a0dc50104e03ecadd1fd1902b27be6b9c0c8/mobile/android/chrome/geckoview/SessionStateAggregator.js but we'll have to rewrite that for Fission.

Though I am not sure this bug is a right place, with the change in bug 1722485, the NS_ERROR_FILE_NOT_FOUND seems to be fixed, but the timeout (bug 1687739) still happens at window.open(). That's what Agi means in comment 3?