User Agent: Mozilla/5.0 (Windows NT 6.1; rv:50.0) Gecko/20100101 Firefox/50.0 Build ID: 20100101 Steps to reproduce: I am using Firefox Nightly 56.0a1 (2017-06-23) (64-bit) on macOS Sierra. To reproduce the bug, just quit a maximised Firefox session and then reopen the application. Actual results: Firefox opens and restores the previous session as usual, but the window size is not restored. I have attached a screenshot showing how Firefox appears when opened. Expected results: The previous window size (maximised, in my case) should have been remembered and restored.

(and sorry, my reported user agent is wrong, probably Random Agent Spoofer messed it up in the past.)

I can't reproduce the problem you're having here, Matt! Perhaps you can share the contents of the about:support page in Firefox install? Does this also happen when you disable your addons (i.e. safe mode)?

Hi Mike! The problem is still happening in version 55. I have refreshed my profile, etc., but it keeps happening. Starting Firefox in safe mode doesn't solve the issue. These are the contents of about:support. { "application": { "name": "Firefox", "osVersion": "Darwin 16.7.0", "version": "55.0.3", "buildID": "20170824053838", "userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:55.0) Gecko/20100101 Firefox/55.0", "safeMode": true, "updateChannel": "release", "supportURL": "https://support.mozilla.org/1/firefox/55.0.3/Darwin/en-GB/", "numTotalWindows": 1, "numRemoteWindows": 1, "remoteAutoStart": true, "currentContentProcesses": 0, "maxContentProcesses": 4, "autoStartStatus": 1, "keyGoogleFound": true, "keyMozillaFound": true }, "modifiedPreferences": { "accessibility.typeaheadfind.flashBar": 0, "browser.cache.disk.filesystem_reported": 1, "browser.cache.disk.smart_size.first_run": false, "browser.cache.frecency_experiment": 3, "browser.cache.disk.smart_size.use_old_max": false, "browser.cache.disk.capacity": 358400, "browser.places.smartBookmarksVersion": 8, "browser.search.useDBForOrder": true, "browser.sessionstore.upgradeBackup.latestBuildID": "20170824053838", "browser.startup.homepage_override.mstone": "55.0.3", "browser.startup.homepage_override.buildID": "20170824053838", "browser.tabs.remote.autostart.2": true, "browser.urlbar.lastSuggestionsPromptDate": 20170911, "browser.urlbar.timesBeforeHidingSuggestionsHint": 0, "dom.battery.enabled": false, "dom.ipc.processCount": 4, "extensions.lastAppVersion": "55.0.3", "media.gmp-widevinecdm.abi": "x86_64-gcc3", "media.gmp-gmpopenh264.abi": "x86_64-gcc3", "media.gmp-manager.lastCheck": 1505476711, "media.gmp.storage.version.observed": 1, "media.gmp-widevinecdm.version": "1.4.8.903", "media.webrtc.debug.log_file": "/var/folders/ym/_gxznzm12l92krf2v2_nplc80000gn/T/WebRTC.log", "media.gmp-gmpopenh264.version": "1.6", "media.peerconnection.ice.default_address_only": true, "media.benchmark.vp9.versioncheck": 2, "media.gmp-manager.buildID": "20170824053838", "media.benchmark.vp9.fps": 82, "media.gmp-widevinecdm.lastUpdate": 1505123654, "media.peerconnection.ice.no_host": true, "media.gmp-gmpopenh264.lastUpdate": 1505123649, "network.prefetch-next": false, "network.dns.disablePrefetch": true, "network.predictor.enabled": false, "network.predictor.cleaned-up": true, "network.IDN_show_punycode": true, "network.cookie.prefsMigrated": true, "network.http.speculative-parallel-limit": 0, "places.database.lastMaintenance": 1505133238, "places.history.expiration.transient_current_max_pages": 127616, "plugin.disable_full_page_plugin_for_types": "application/pdf", "plugins.ctprollout.cohortSample": "0.130759", "plugins.ctprollout.cohort": "test", "privacy.trackingprotection.pbmode.enabled": false, "privacy.resistFingerprinting": true, "security.sandbox.content.tempDirSuffix": "{3a048598-dcdc-814b-bb95-577f19b7a9f8}", "services.sync.declinedEngines": "", "storage.vacuum.last.index": 1, "storage.vacuum.last.places.sqlite": 1505133238 }, "lockedPreferences": {}, "javaScript": { "incrementalGCEnabled": true }, "accessibility": { "isActive": false, "forceDisabled": 0 }, "libraryVersions": { "NSPR": { "minVersion": "4.15", "version": "4.15" }, "NSS": { "minVersion": "3.31.1", "version": "3.31.1" }, "NSSUTIL": { "minVersion": "3.31.1", "version": "3.31.1" }, "NSSSSL": { "minVersion": "3.31.1", "version": "3.31.1" }, "NSSSMIME": { "minVersion": "3.31.1", "version": "3.31.1" } }, "userJS": { "exists": false }, "crashes": { "submitted": [], "pending": 0 }, "sandbox": { "contentSandboxLevel": 1, "effectiveContentSandboxLevel": 1 }, "graphics": { "numTotalWindows": 1, "numAcceleratedWindows": 0, "windowLayerManagerType": "Basic", "windowLayerManagerRemote": true, "currentAudioBackend": "audiounit", "numAcceleratedWindowsMessage": [ "" ], "adapterDescription": "", "adapterVendorID": "0x8086", "adapterDeviceID": "0x1626", "adapterRAM": "", "adapterDrivers": "", "driverVersion": "", "driverDate": "", "webgl1Renderer": "WebGL is currently disabled.", "webgl1Version": "-", "webgl1DriverExtensions": "-", "webgl1Extensions": "-", "webgl1WSIInfo": "-", "webgl2Renderer": "WebGL is currently disabled.", "webgl2Version": "-", "webgl2DriverExtensions": "-", "webgl2Extensions": "-", "webgl2WSIInfo": "-", "info": { "AzureCanvasBackend": "skia", "AzureFallbackCanvasBackend": "none", "AzureContentBackend": "skia", "AzureCanvasAccelerated": 0, "ApzWheelInput": 1, "ApzDragInput": 1, "TileHeight": 512, "TileWidth": 512 }, "featureLog": { "features": [ { "name": "HW_COMPOSITING", "description": "Compositing", "status": "blocked", "log": [ { "type": "default", "status": "available" }, { "type": "runtime", "status": "blocked", "message": "Acceleration blocked by safe-mode" } ] }, { "name": "OPENGL_COMPOSITING", "description": "OpenGL Compositing", "status": "unavailable", "log": [ { "type": "default", "status": "unavailable", "message": "Hardware compositing is disabled" } ] }, { "name": "WEBRENDER", "description": "WebRender", "status": "unavailable", "log": [ { "type": "default", "status": "opt-in", "message": "WebRender is an opt-in feature" }, { "type": "runtime", "status": "unavailable", "message": "Build doesn't include WebRender" } ] } ], "fallbacks": [] }, "crashGuards": [] }, "experiments": [], "extensions": [ { "name": "Decentraleyes", "version": "1.3.10", "isActive": false, "id": "jid1-BoFifL9Vbdl2zQ@jetpack" }, { "name": "Privacy Badger", "version": "2017.9.12.1", "isActive": false, "id": "jid1-MnnxcxisBPnSXQ@jetpack" }, { "name": "uBlock Origin", "version": "1.14.8", "isActive": false, "id": "uBlock0@raymondhill.net" }, { "name": "Zotero Connector", "version": "5.0.19", "isActive": false, "id": "zotero@chnm.gmu.edu" } ], "features": [ { "name": "Application Update Service Helper", "version": "2.0", "id": "aushelper@mozilla.org" }, { "name": "Click-to-Play staged rollout", "version": "1.2", "id": "clicktoplay-rollout@mozilla.org" }, { "name": "Firefox Screenshots", "version": "10.12.0", "id": "screenshots@mozilla.org" }, { "name": "Follow-on Search Telemetry", "version": "0.9.1", "id": "followonsearch@mozilla.com" }, { "name": "Multi-process staged rollout", "version": "2.0", "id": "e10srollout@mozilla.org" }, { "name": "Pocket", "version": "1.0.5", "id": "firefox@getpocket.com" }, { "name": "Shield Recipe Client", "version": "55.1", "id": "shield-recipe-client@mozilla.org" }, { "name": "Web Compat", "version": "1.1", "id": "webcompat@mozilla.org" } ] }

Matt, are you still seeing this problem? (Quite a few things have changed in the meantime, hence my question.)

(In reply to Mike de Boer [:mikedeboer] from comment #4) > Matt, are you still seeing this problem? (Quite a few things have changed in > the meantime, hence my question.) No, I don't. I cannot say when the problem disappeared, but at a certain point it stopped happening. I'm currently using Firefox 59.0.2 and I don't experience the issue anymore. Thanks! Matteo

Sweet! Thanks for the quick reply!