Boeing will need to win back the trust of customers, passengers and regulators following the crashes.
Test pilots made 146 737 MAX flights totaling roughly 246 hours of air time with the updated software.
More than 300 Boeing 737 MAX jets have been grounded worldwide.
Gone in 6 minutes: Ethiopian Airlines pilots struggled with Boeing's anti-stall system from first minute after takeoff, says initial report
From nearly the moment they roared down the runway and took off in their new Boeing jetliner, pilots of an Ethiopian Airlines flight encountered problems with the plane.
Will take all steps to enhance security, Boeing assures hours after probe into Ethiopia crash reveals flight's sensor had sent faulty data
The statement came hours after Ethiopian investigators said the pilots of a doomed Boeing 737 MAX 8 had repeatedly followed Boeing's recommended procedures prior to crashing on 10 March.
Pilot of ill-fated Ethiopian Airlines plane requested permission to return to airport minutes after taking off: Report
An airline spokesman has said pilot of the Ethiopian Airlines plane was given permission to return. But the plane crashed minutes later, outside Addis Ababa, killing all 157 on board
Ethiopian Airlines says it 'has flown' black boxes of crashed Boeing 737 MAX 8 to Paris for investigation into 10 March crash
"An Ethiopian delegation led by Accident Investigation Bureau (AIB) has flown the Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) to Paris, France for investigation," the airline wrote on Twitter.
Donald Trump confirms US grounding Boeing 737 Max 8, 9 after Ethiopia crash, 'effective immediately'
The US is issuing an emergency order Wednesday grounding all Boeing 737 Max 8 and Max 9 aircraft "effective immediately," in the wake of the crash of an Ethiopian Airliner that killed 157 people, President Donald Trump said.
Ethiopian Airlines to send black boxes of 'crashed' Boeing abroad, after two-thirds of all 737 MAX planes were grounded globally
Boeing, the world’s biggest planemaker, has said it retains "full confidence" in the 737 MAX. Its shares fell 6.1 percent on Tuesday, bringing losses to 11.15 percent since the crash.
Boeing 737 MAX 8: The world's most successful commercial jetliner is in trouble, but nobody knows what's wrong
The Boeing Company, maker of the 737, also happens to be one of the world’s oldest aircraft makers.
Ethiopian Airlines, Lion Air plane crash: Anti-stalling system on Boeing's 737 Max 8 under scanner as countries ground aircraft
Boeing has described the Max series as its fastest-selling family of planes, with more than 5,000 orders placed to date from about 100 customers.
Grounding Boeing 737 MAX 8 isn't the answer, fixing accountability and rooting out issues with aircraft key to allay panic
Boeing has been quiet about the crash, but on Monday the FAA advised that there would be software upgrades to the MCAS on board all Boeing 737 MAX aircraft by the end of April 2019.
India grounds Boeing 737 MAX aircraft after Ethiopian Airlines crash: Here's a list of countries that have put the plane on ice
Boeing has delivered more than 200 737 MAXs since May 2017, news reports said.
Boeing 737 Max grounding: Aviation Ministry calls meeting at 4 pm with airlines for contingency plan
A number of flights have been cancelled following the grounding of Boeing 737 Max 8 aircraft,
Daily Bulletin: UNSC likely to designate Masood Azhar a global terrorist; election trail heats up as candidates lists appear; day's top stories
Day's top stories: The UNSC is likely to include Jaish-e-Mohammed chief Masood Azhar in its global terrorists list unless China objects; Congress president Rahul Gandhi will address the UPA's first rally in Tamil Nadu; India likely to ban the Boeing 737 Max 8 aircraft following the Ethopia crash; and more.
Ethiopian Airlines crash: US says Boeing 737 MAX safe to fly while China, Indonesia ground fleet; investigators find two black boxes
The United States told airlines it was safe to fly 737 MAX 8 planes on Monday as investigators found two black box recorders that will help piece together the final moments of an Ethiopian Airlines jet before it plunged to the ground on Sunday.
Boeing 737 Max 8s under intense scrutiny after Ethiopia crash; China grounds these planes as part of 'zero tolerance' policy
Airlines in Ethiopia, China, Indonesia and elsewhere grounded the Boeing 737 Max 8 jetliner Monday after the second devastating crash of one of the planes in five months. But Boeing said it had no reason to pull the popular aircraft from the skies.
China grounds all Boeing 737s after Ethiopian Airlines crash, cites similarities with Lion Air tragedy in October
China on Monday ordered domestic airlines to suspend commercial operation of the Boeing 737 MAX 8, citing the Ethiopian Airlines crash and another deadly accident of that same model in Indonesia.
Ethiopian Airlines crash: Pilot mentioned difficulties soon after takeoff and ‘wanted to return’, says carrier's CEO
An Ethiopian Airlines passenger jet bound for Nairobi crashed minutes after take-off on Sunday, killing all 157 people on board and raising questions about the safety of the Boeing 737 MAX 8, a new model that also crashed in Indonesia in October.
Indonesia flight crash: Boeing vows to share investigation information with customers amid reports of cancelled conference call
US media reported that the cancelled conference between Boeing and client companies was meant to address questions surrounding control systems on the Lion Air 737-MAX. "Boeing has been - and continues to - engage with our customers," a spokesman for the US aircraft manufacturer told AFP. "We continue to schedule meetings to share information."