As flight testing took longer than expected, the scheduled entry into service was further pushed back until development was first paused in October 2020, and subsequently cancelled altogether in February 2023.

In 2003 the Japanese government started a five-year, ¥50 billion ($420 million) research program to study an indigenous regional jet for 30 to 90 passengers, led by Mitsubishi Heavy Industries (MHI).

[8] MHI officially launched the Mitsubishi Regional Jet program on March 28, 2008, with an order for 25 aircraft (15 firm, 10 optional) from All Nippon Airways, targeting a 2013 introduction.

[17] Mitsubishi worked on a three-class, 76-seat design, with more premium seating than the MRJ70 but still within the scope-clause 86,000 lb (39 t) MTOW, to be unveiled at the June 2019 Paris Air Show.

[23] A new production facility for the aircraft was built at Komaki Airport in Nagoya, Japan, on land purchased from the government at a total cost of 60 billion yen.

[23] Mitsubishi announced in June 2013 that it would establish a quality control facility in Illinois for the sourcing of MRJ components from the United States.

[32] MHI employed new production methods such as integral wing stringers, unusually tight tolerances, shot peening of curved surfaces, and vacuum assisted resin transfer molding, intended to increase quality and thus reduce expensive fault correction to keep price competitive.

[37] Much of the flight testing for the MRJ90 took place in Moses Lake, Washington, at the Grant County International Airport, due to the crowded airspace in Japan causing scheduling difficulties.

[43] On 26 April 2017, the fifth MRJ was complete in ANA livery, lacking only engines and nose cone, aircraft number six and seven had their fuselage and wings joined without the tails, and the eighth, the first MRJ70, was at the assembly line start; Mitsubishi planned to manufacture 12 aircraft concurrently: in station one are joined fuselage sections, in station two the landing gear, wings and horizontal stabilisers are attached, in section three the major components are assembled, in outfitting takes place in section four and ground tests in station five, then the completed aircraft moves to painting.

saw problems for avionics and its wiring certification: damage could cause single point of failure, due to fire, water flooding from a ruptured waterline, or from part penetration of an engine explosion.

[44] On 21 August, FTA-2 experienced a flameout 170 km (92 nmi) west of Portland International where it landed; partial damage was confirmed in the PW1200G and the test fleet was grounded until the cause was known.

[47] Two additional aircraft (10007 and 10010), recently painted white and under structural assembly in December, were expected to join the flight test campaign towards the end of 2018.

[49] In January 2018, the avionics bay rearrangement and rerouted wiring were almost complete to be adequate for extreme events such as bomb explosions or water ingress underfloor.

[52] The flight-test fleet attained 2,000 hours in May 2018, and as most of the flight envelope was explored, the next trimester shifted to runway performance: takeoff, landing and minimum control speeds.

[17] An MRJ in All Nippon Airways livery was exhibited at the July Farnborough Airshow, alongside appearances by the similar Embraer 190 E2 and larger Airbus A220.

[58] By December 2018, the Japan Civil Aviation Bureau delivered its type inspection authorisation, allowing to debut certification flight testing in early 2019 with the four MRJ90 in Moses Lake.

Compared to the E175-E2, the M100 cabin is a tighter fit around its 76 seats, and its wing is lighter, having 3.2 m (10 ft) less span and with smaller winglets than the MRJ90, giving it 50% more fuel than the E175-E2 at the MTOW limit for a 1,500 nmi (2,800 km) range with 76 passengers.

The shorter span would allow operation at Colorado's Aspen/Pitkin County Airport, a popular tourist destination; the CRJ700 was the last jet in production to have the capability, until approval for Skywest E175 in late 2024.

[68] In October 2020, Mitsubishi announced a further budget reduction and a "temporary pause" to most SpaceJet activities other than type certification documentation while it assessed a "possible program restart.

[71] In October 2021, the manufacturer confirmed to the Federal Aviation Administration that it did not plan to restart development and production of the SpaceJet in the foreseeable future.

During the 2013 Regional Airlines Association conference, held in Montreal, Quebec, Canada, Mitsubishi announced that ANI Group Holdings, which firmed a MoU for 5 MRJ aircraft in June 2011, cancelled the deal, without giving further details.

[88] The MRJ's future was uncertain after six years of delays, with 70% of the backlog shared by two US regional carriers bound by scope clauses: the MRJ90 is too heavy and the smaller MRJ70 accommodates seven fewer seats than the 76 permitted.

[91] On 5 September 2019, US regional carrier Mesa Airlines signed a Memorandum of Understanding for up to 100 SpaceJet M100s, 50 of which were targeted as firm orders and 50 as purchase rights.

[92] On 31 October 2019, Trans States Holdings cancelled its order for 100 MRJ90s (50 firm, 50 optional) because the aircraft did not comply with US airlines' scope clauses.