It fails the Debian Free Software Guidelines,[1] used by several Linux distributions, though it qualifies for the FSF's Free Software Definition; however, it is incompatible with the FSF's GPL,[2] meaning that products derived from code under both the GPL and the QPL cannot be redistributed.
Only the free open source edition of Qt was covered by the QPL; the commercial edition, which is functionally equal, is under a pay-per-use license and could not be freely distributed.
[2] As KDE grew in popularity, the free software community urged Trolltech to license Qt under the GPL to ensure that it would remain free software forever and could be used and developed by commercial third parties.
Eventually, under pressure, Trolltech dual-licensed the free edition of Qt 2.2 for use under the terms of the GPL or the QPL.
[3] Other projects that have adopted the Q Public License, sometimes with a change in the choice of jurisdiction clause, include: Prior projects using the Q Public License include: The Debian project rejects software covered by solely QPL[1] (and not dual licensed with something else like the GPL) because of: All legal disputes about the license are settled in Oslo, Norway,[6] but it has never been legally contested.