As has become customary around this time of year, a huge batch of updated forms have been released by UKVI.
Applications must be made on the current version of a form in order to be considered 'valid', though it is worth bearing in mind that under paragraph 34(2)(c) of the Immigration Rules an application can be made on a previous version of a specified paper application form (and shall be treated as made on a specified form) as long as it is no more than 21 days out of date. This allows those who have perhaps already completed one of the old version forms to validly submit their application before 15 December. It is however always recommended that the newest version of the form is used and whilst some of the forms are tortuously long, it would still be advisable to complete the up-to-date version rather than seek to rely on an old version.
New forms have been published online this morning for the following applications: