Clone commander Cody received the order to strike down the Jedi general; Obi-Wan, who was traversing up a cliff on a reptilian mount, was blasted into a river and managed to escape the turbulent waters.
Though the Jedi can use the Force to sense danger, they couldn't foresee Order 66 because their judgement was clouded by their hypocrisy.
The Jedi Order survived through the acts of surviving Jedi, such as Obi-Wan Kenobi and Yoda, passing on the ways of the Force and the Jedi to promising Force-sensitives such as Luke Skywalker.
In a change from Star Wars Legends, the Obi-Wan Kenobi series made it clear that Kenobi went ten years thinking that Darth Vader was dead.
Arguably, most Star Wars plot points revolve around characters simply not knowing something, very often about their family history. But, on top of all of that, the biggest reason Obi-Wan doesn't know Anakin is alive is that the last time he saw Anakin Skywalker in Revenge of the Sith, Ben literally left him for dead.
Anakin admits to Obi-Wan that he has been arrogant and unappreciative of his training, and apologizes to his master. Obi-Wan assures Anakin that he is proud of him, telling him that he has become a "far greater Jedi than I could ever hope to be."
The two biggest have been Trilla Suduri, known as the Second Sister from Star Wars Jedi: Fallen Order, and Reva Sevander, also known as Third Sister from Obi-Wan Kenobi. Other Inquisitors have been featured across the canon, acting as Jedi hunters under the command of the Grand Inquisitor and Darth Vader himself.
By the end of The Rise of Skywalker, Rey had become the last known Jedi of the Skywalker Saga. With all that being said, Rey was not left as the last remaining Force-sensitive character.
Order 67 was an order requiring clone troopers to dance. During the Battle of Utapau, Darth Sidious accidentally issued Order 67 when he meant to use Order 66. Just after the order was executed, Cody and his troops began dancing.
To summarise: Master Yoda could not warn the other Jedi about Order 66 because he did not know about it until it happened. He knew the Jedi would die, just not how or when the blade would drop.
Some clones disobeyed the infamous order than decimated the Jedi order, and refused to execute it. SOME of these Clones include; Captain Rex: Captain Rex, as most know removed his chip that would later be the way that Palpatine would execute order 66. Wolffe: As with Captain Rex Wolffe removed his bio chip.
Star Wars revealed that Yoda received a warning about Order 66 at the start of the Clone Wars, making it unclear why the Jedi Master chose to ignore it. Order 66 wiped out most of the Jedi Order, so if Yoda knew about it in advance, then he could have taken steps to make sure it didn't happen.
Soon the beaches were littered with inert droids, burned-out vehicles and dead Wookiees and clones. When Supreme Chancellor Palpatine issued Order 66, Unduli was captured and taken into custody by the clones she'd once commanded. But Yoda escaped with the assistance of Tarfful and Chewbacca.
Zatt was a Nautolan male Jedi Padawan and a survivor of Order 66. He died in battle against the Dark Side Adept Tau Pei on Ilum during the reign of the Galactic Empire.
Thousands of Jedi throughout the galaxy were killed, including Ki-Adi-Mundi on Mygeeto, Aayla Secura on Felucia, Plo Koon in the skies of Cato Neimoidia, Stass Allie on Saleucami, Depa Billaba on Kaller, Jaro Tapal in the Bracca system, and even Jedi younglings.
Following Palpatine's final defeat and her own resurrection, Rey adopts the name Rey Skywalker to honor her mentors and their family legacy and renounce her lineage. As the last remaining Jedi, she makes it her mission to rebuild the Jedi Order.
Yoda is widely considered to be the greatest Jedi of all time, and with good reason. He is a master of the Force, a skilled warrior, and has an unmatched wisdom that comes from centuries of experience. He is the embodiment of what it means to be a Jedi, and his legacy lives on long after his death.
What is the connection between Kylo Ren and Rey? As Kylo Ren himself says in The Rise of Skywalker, he and Rey are bonded not just by their familial legacies (Ren as the grandson of Darth Vader and Rey as the granddaughter of Emperor Palpatine) but by their unique connection in the Force.
Yoda claims to have been training Jedi for 800 years. The second time Yoda mentions his long life is in Return of the Jedi, when he tells Luke, “When you reach 900 years old, you will not look as good as you will.” If we take Yoda at his word, that means the Jedi Master died at the ripe old age of 900.
Yoda. Yoda was a wise, experienced, and powerful Grand Master of the Jedi of an unknown species and the oldest known prophet in existence (having lived at least 900 years), considered the wisest and most powerful Jedi Master within the Star Wars universe.
Order 65 stated that if a majority of the Senate or the Security Council declared that the Supreme Chancellor—at that time Palpatine—was unfit for duty, the Chancellor was to be arrested or, if necessary, killed.
He slays Sidious and returns to Obi-Wan, begging for atonement by execution, only to be met with true forgiveness instead. But just as this fantasy Obi-Wan refuses to strike his former friend down, Vader refuses to turn his back on the dark.
First and foremost, Obi-Wan didn't want to have to confront and try to kill Anakin, we see this all the way until their final conflict in their duel where Obi-Wan pleads with Anakin to not make him do what he knows he'll have to do if Anakin tries to attack from the low-ground.
He couldn't bring himself to kill Darth Vader, however, because he continues to associate him with the Anakin he trained as a boy. This is also the exact reason why Obi-Wan didn't kill Anakin on Mustafar despite the opportunity a decade earlier in Star Wars: Episode III - Revenge of the Sith.