Wizards of the Coast has announced that the release date for Dungeons and Dragons:  The Rise of Tiamat will slip two weeks, to November 4 (from October 21).  Stores participating in the early release program will receive the volume on October 24. 

Quality problems with the test printing are causing the delay, according to the announcement.  "The test print run didn’t match our quality expectations and even though addressing these issues has caused a delay we must put out the highest quality products we can," the announcement said. 

The Rise of Tiamat is the fifth of the first six D&D 5E products announced (see "New 'D&D' Dates, Info, and Pics").  The new Dungeon Master’s Guide was pushed back from November to December earlier this month (see "'D&D: DM Guide' Delayed").  The reason cited in that case was a longer quality control cycle on the new range of books.