As most may remember - On April 20th, SpaceX's Crew Dragon spacecraft exploded at their landing zones during the abort motor testing of the recently-recovered spacecraft from the DM-1 mission. This was meant to do tests of the abort system after recovery ahead of using that capsule for the In-Flight Abort test they had planned to do a month later.
The explosion of Crew Dragon turned many heads and many people questioned the safety of Dragon. SpaceX and NASA have been working very closely over the last 3 months and have finally released their official update on the investigation, which can be found here.
To sum up most of it, a leak allowed Liquid Oxygen and Nitrogen Tetroxide (NTO) to enter the high-pressure helium tubes and NTO got pushed through one of the check valves, which caused that valve to fail. Later testing at SpaceX's rocket test site in McGregor, TX showed that NTO has an intense reaction with titanium at high pressures, which wasn't expected. This test is not only beneficial to SpaceX's progression with Crew Drago, but for the whole aerospace industry as a whole. This valuable information will ensure this similar situation doesn't occur again during development of other vehicles and spacecraft in the future.
The Helium check valves have now been replaced with burst disks to ensure this failure doesn't happen again.
As for the schedule of Crew Dragon, Hans Koenigsmann, SpaceX's Vice President of Mission Assurance, said "We fly when we're ready". They think they can manage having DM-2, the first crewed mission for Dragon, fly by the end of the year, but it'll be extremely difficult.
As the investigation of this anomaly comes to a close, we are reminded that spaceflight is hard and failures will happen. Boeing's Starliner spacecraft also had major issues with their abort system. It seems that switching from conventional solid motor escape towers to hypergolic escape motors built into the capsule has been a big hurdle to get over, but it seems both companies have managed to work past their failures and progress the US to sending humans into space from Florida once again.