The entire 1,230-game schedule, that was set to begin in October, was officially canceled on February 16, 2005, due to an unresolved lockout that began on September 16, 2004.

[3] According to the International Ice Hockey Federation, 388 NHL players were on teams overseas at some point during the season, spread across 19 European leagues.

On July 5, 2004, the AHL announced publicly the 2004–05 rule changes, many of which were passed as a result of the NHL's recommendation for experimentation.

The action marked the third labour dispute between the league and the NHLPA in twelve years, following the 1992 strike and the 1994–95 lockout.

[6] According to an NHL-commissioned report prepared by former U.S. Securities and Exchange Commission chairman Arthur Levitt, prior to 2004–05, NHL clubs spent about 76 percent of their gross revenues on players' salaries – a figure far higher than those in other North American sports – and collectively lost US$273 million during the 2002–03 season.

[9] The NHLPA, under executive director Bob Goodenow, however disputed the league's financial claims and rejected each of the NHL's proposed six concepts.

As a result of the lockout, no Stanley Cup champion was crowned for the first time since the Spanish flu pandemic in 1919.

[15] Adrienne Clarkson, then Governor General of Canada, alternately proposed that the Cup be presented to the top women's hockey team in lieu of the NHL season, but this idea was so unpopular with NHL fans, players, and officials that the Clarkson Cup was created instead.

[16] Meanwhile, a group in Ontario, also known as the "Wednesday Nighters", filed an application with the Ontario Superior Court, claiming that the Cup trustees had overstepped their bounds in signing the 1947 agreement with the NHL, and therefore must award the trophy to any team willing to play for the cup regardless of the lockout.