Release Date Change

A Release Date Change is what happens when a certain work gets delayed or pushed back from its original announced date of release. Out of the many Executive Meddling moves, this is probably the most visible among the public.

Most of the time, this is due to the work having fallen into a Troubled Production or Development Hell, but just as often this is inflicted on finished works for whom corporate mandate decided that its original announced date of release is not convenient anymore. Then there's the element of real-world "interference", such as the COVID-19 pandemic that started in 2020 and drastically altered the entire entertainment industry schedule due to the widespread lockdowns and quarantines enacted to avoid the spread of said illness.

Sometimes this can be the result of Too Soon kicking in, while other times can be the result of trying to avoid direct competition with bigger (or similarly themed) releases, or trying to get advantage of commercial holidays that can attract consumers towards the work. While most cases involve the work being released in a later date, there have been some notorious cases where the release was actually moved to an earlier date, usually because of spoilery leaks.

Super-Trope to Development Hell, where the date change happens because of a Troubled Production's pre-production delays; The Shelf of Movie Languishment, where the date change happens because of post-production delays; Schedule Slip, where the date change happens to an installment after the first in a serial work; and Vaporware, where the date change happens because the product doesn't exist yet.

Compare with Real Soon Now, where there is no scheduled release date.

Examples of Release Date Change include:

Film

Bad Company would have been released on Christmas 2001 but due to 9/11, the film was eventually released on June 7th, 2002.
Fantastic Four was going to be released on July 4th, 2005 but got delayed to July 8th, 2005.
Frozen II‍'‍s digital release on Disney+ was moved earlier from June 26, 2020 to March 15, 2020 due to the COVID-19 pandemic.
Gangs of New York got delayed from December 21, 2001 to December 25, 2002 because of the World Trade Center being shown in the final shot.
Hoodwinked would have been released at more screenings on Christmas 2005 but got delayed to January 2006.
No Time to Die was originally going to be released on November 2019 but due to the stepping down of a producer and the COVID-19 pandemic, it got delayed two whole years.
Shark Tale was intended to be released on November 5th, 2004 but got pushed back to October 1st, 2004 to prevent competition with The Incredibles.
Sonic the Hedgehog was delayed from November 2019 to February 14th, 2020, due to the team redesigning Sonic to make him look more like his video game self.
Teacher's Pet -- the feature length film of the Disney TV series -- would have been released on December 2003, but got delayed to February 2004 before getting pushed back up to January 2004.
The Time Machine was delayed from December 2001 to March 2002 to prevent competition with The Lord of the Rings: The Fellowship of the Ring and due to 9/11.
Training Day was delayed from September 21, 2001 to October 5, 2001 due to 9/11.

Live-Action TV

Buffy the Vampire Slayer had two episodes, Earshot and Graduation Day Part 2, which were delayed from their original airdates to September 1999 and July 1999 respectively, due to the Columbine High School massacre.
The 53rd Annual Primetime Emmy Awards, which were originally scheduled to be aired on September 16, 2001, were delayed because of the 9/11 attacks to October 7 - at which point they were preempted for news of the USA bombing Afghanistan. The award show was finally held on November 4.

Video Games

The Legend of Zelda: Twilight Princess was intended to be released on 2005 as a Nintendo GameCube exclusive, but got delayed to 2006 as a Nintendo Wii launch title in addition to the original GameCube version.
Duke Nukem Forever is the epitome of this trope, as it was "coming soon" for 14 years before finally being released in June 2011 (and even then that was a setback of one month, a fact the developers readily lampshaded).
All Blizzard Entertainment products have a release time of "Soon™": Diablo III wasn't released until May 2012, after having been initially announced in 2008. Diablo IV was announced in 2019 to be released on 2021, and as of mid-2021 still doesn't have an actual release date save for a vague "probably before the year ends".
- Averted with World of Warcraft expansion Cataclysm when it was released prior to 2011 on December 7, 2010. It was an Obvious Beta compared to other expansions, but after Burning Crusade had to be pushed back to 2007 (original release date was sometime in November 2006) and the game was playable, they decided to launch it.
- Ongoing controversy (as of November 20th, 2021) surrounding CEO Bobby Kotick and his role in covering up years of alleged sexual assault - among other scandals - might keep Diablo IV and other teased releases shelved for quite a while, to say the least.
Valve, the developers of Half-Life, Team Fortress 2, and Left 4 Dead are particularly infamous for continued delays on their release dates - so much so that their fandom has coined the term "Valve Time" to refer to the manner in which they can single-handedly dilate time around themselves. This is probably mostly thanks to Valve's loose internal corporate structure, where no-one has a single set-in-stone role to play in the company. They claim it is due to their attempts to produce high-quality games that are fun, and the developer commentary often mentions features that were not fun that had to be discarded, which certainly consumes time.

Valve time for Episode 3:
Announcement: Christmas of 2007
Actual: Coincident with the Rapture (no, not that one)

Averted with Left 4 Dead 2. Valve intentionally released the game on a fixed schedule (literally a year after the first game was released) to prove they can release on time. Fans to this day still argue whether or not this was a good thing, due to several issues the game brought up.
In some cases like the above, there's also "Reverse Valve Time".

Daikatana. "Come hell or high water, the game will be done on February 15, 1999." Its actual release date: April 14, 2000.
Super Smash Bros. Brawl was announced in 2006 and set for a 2007 release. But because they already had one third-party character in the game (Snake), and fans demanded another third-party character to be added to the game (Sonic the Hedgehog), the game had to be delayed until Feb. 2008. Then when February was near, the game was delayed until March because they wanted to work out some bugs in the online system, and so the game finally saw a release in March.
Kid Icarus: Uprising also went through several delays. It was initially announced in 2010 as a launch title for the Nintendo 3DS, but when the 3DS's launch neared, it was delayed until August of that year. August came around, and the game was delayed until November or December. Then it was delayed until early 2012, which was when it was finally released.
Metal Gear Solid 4: Guns of the Patriots. A 2006 trailer announced it would be released in 2007, but it wasn't released until 2008.
Working Designs was notorious for this. ADV Films delayed the Arc the Lad anime to come out the same time as the game; at that point, they had already been late so often that the Genre Savvy could have predicted that wouldn't work. Magic Knight Rayearth also ended up being the last game for the Sega Saturn because of various delays.

Western Animation

Hi Hi Puffy AmiYumi was supposed to premiere on Cartoon Network in December 2004 but got pushed back to November 19th, 2004.