What problem did Edward the confessor leave behind?

Answer 1

The huge problem that King Edward the Confessor left behind was his broken word over naming a successor to the English throne.

Twice in public, King Edward confirmed to William of Normandy that he would name William as his successor. He also made this agreement personally with William in private.

On his deathbed, King Edward reneged on his word and named Harald Godwineson, a newphew by marriage, but not by blood. King Edward then left behind the problem of a broken, royal vow, to a legitimate blood heir to the crown in favor of one who had no blood claim on the crown.

This resulted in The Battle of Hastings in 1066 that changed the British landscape forever and the Conquest of England by William of Normandy, the Conqueror.

Answer 2

That he had not had an heir so there were worries about who would be the next king.