After update from: 70.0+build2-0ubuntu0.16.04.1 to 71.0~b5+build1-0ubuntu0.16.04.1 app is not starting. I got constantly message that I can Refresh Firefox (crash) or Start in safe mode (also crash).
Tech details:
Description: Ubuntu 16.04.6 LTS
Release: 16.04
package name: 71.0~b5+build1-0ubuntu0.16.04.1
Crash log details:
AdapterDeviceID: 0x1616
AdapterDriverVendor: mesa/i965
AdapterDriverVersion: 18.0.5.0
AdapterVendorID: 0x8086
BuildID: 20191028161640
ContentSandboxCapabilities: 119
ContentSandboxCapable: 1
ContentSandboxLevel: 4
CrashTime: 1572373123
DOMIPCEnabled: 1
FramePoisonBase: 9223372036600930304
FramePoisonSize: 4096
InstallTime: 1572364967
IsWayland: 0
IsWaylandDRM: 0
MozCrashReason: MOZ_RELEASE_ASSERT(len.isValid()) (Substring tuple length is invalid)
Notes: Ubuntu 16.04.6 LTSFP(D00-L1000-W00000000-T000) WR? WR- OMTP? OMTP-
ProductID: {ec8030f7-c20a-464f-9b0e-13a3a9e97384}
ProductName: Firefox
ReleaseChannel: beta
SafeMode: 1
SecondsSinceLastCrash: 816
StartupCrash: 0
StartupTime: 1572373025
TelemetryEnvironment: {"build":{"applicationId":"{ec8030f7-c20a-464f-9b0e-13a3a9e97384}","applicationName":"Firefox","architecture":"x86-64","buildId":"20191028161640","version":"71.0","vendor":"Mozilla","displayVersion":"71.0b5","platformVersion":"71.0","xpcomAbi":"x86_64-gcc3","updaterAvailable":false},"partner":{"distributionId":null,"distributionVersion":null,"partnerId":null,"distributor":null,"distributorChannel":null,"partnerNames":[]},"system":{"memoryMB":15965,"virtualMaxMB":null,"cpu":{"count":4,"cores":2,"vendor":"GenuineIntel","family":6,"model":61,"stepping":4,"l2cacheKB":256,"l3cacheKB":3072,"speedMHz":2700,"extensions":["hasMMX","hasSSE","hasSSE2","hasSSE3","hasSSSE3","hasSSE4_1","hasSSE4_2","hasAVX","hasAVX2","hasAES"]},"os":{"name":"Linux","version":"4.15.0-66-generic","locale":"en-US"},"hdd":{"profile":{"model":null,"revision":null,"type":null},"binary":{"model":null,"revision":null,"type":null},"system":{"model":null,"revision":null,"type":null}},"gfx":{"D2DEnabled":null,"DWriteEnabled":null,"ContentBackend":"Skia","Headless":false,"adapters":[{"description":"Mesa DRI Intel(R) HD Graphics 5500 (Broadwell GT2) ","vendorID":"0x8086","deviceID":"0x1616","subsysID":null,"RAM":3072,"driver":null,"driverVendor":"mesa/i965","driverVersion":"18.0.5.0","driverDate":null,"GPUActive":true}],"monitors":[{"screenWidth":1366,"screenHeight":768}],"features":{"compositor":"none","gpuProcess":{"status":"blocked"},"wrQualified":{"status":"blocked-release-channel-intel"},"webrender":{"status":"unavailable-in-safe-mode"}}},"appleModelId":null},"settings":{"blocklistEnabled":true,"e10sEnabled":true,"e10sMultiProcesses":8,"telemetryEnabled":true,"locale":"en-US","intl":{},"update":{"channel":"beta","enabled":true,"autoDownload":false},"userPrefs":{"app.shield.optoutstudies.enabled":false,"browser.cache.disk.capacity":1048576,"browser.newtabpage.enabled":false,"browser.shell.checkDefaultBrowser":true,"browser.search.region":"US","browser.search.suggest.enabled":false,"browser.search.widget.inNavBar":false,"browser.startup.homepage":"<user-set>","browser.startup.page":3,"browser.urlbar.suggest.searches":false,"devtools.chrome.enabled":false,"devtools.debugger.remote-enabled":false,"extensions.blocklist.url":"https://blocklists.settings.services.mozilla.com/v1/blocklist/3/%20/%20/","extensions.formautofill.addresses.enabled":false,"extensions.formautofill.creditCards.enabled":false,"privacy.donottrackheader.enabled":true},"sandbox":{"effectiveContentProcessLevel":4},"addonCompatibilityCheckEnabled":true,"isDefaultBrowser":null},"profile":{}}
ThreadIdNameMapping: 7556:"Gecko_IOThread",7557:"JS Watchdog",7558:"JS Helper",7559:"JS Helper",7560:"JS Helper",7561:"JS Helper",7562:"Timer",7563:"Netlink Monitor",7564:"Socket Thread",7568:"Cache2 I/O",7569:"Cookie",7570:"StreamTrans #1",7571:"GMPThread",7572:"Worker Launcher",7573:"SoftwareVsyncThread",7574:"Compositor",7575:"ImgDecoder #1",7576:"ImageIO",7580:"ImageBridgeChild",7581:"IPDL Background",7582:"DOM Worker",7584:"QuotaManager IO",7587:"StyleThread#0",7589:"StyleThread#2",7588:"StyleThread#1",7593:"DOM Worker",7630:"DataStorage",7631:"DNS Resolver #1",7632:"DNS Resolver #2",7633:"StreamTrans #7",7646:"IndexedDB #2",7647:"StreamTrans #8",7648:"StreamTrans #9",7649:"StreamTrans #10",
Throttleable: 1
UptimeTS: 98.30915265
Vendor: Mozilla
Version: 71.0
useragent_locale: en-US
Also I attach crash report from fiferox/ profile/ crashes folder (I don't know if it helps but more info is better).