Some users encounter problems redeeming Apple's Mountain Lion upgrade codes

Some Mac users who are entitled to a free copy of Mountain Lion through Apple's Up-to-Date program have been left frustrated following the operating system's launch.

As part of the program, Apple is offering a free copy of its newly released OS X 10.8 Mountain Lion to customers who purchased a new Mac on or after 11 June. But some users have been forced to wait several days for their redemption codes, while others have received non-working codes.

Worse yet, a number of users have received codes for the OS X 10.8 server tools instead of the operating system installer, The Unofficial Apple Weblog (TUAW) reported on Friday. Many have taken to Twitter and online forums to express frustration over the situation.

"Waiting for a code to get Mountain Lion free via the up-to-date programme, Just called Apple," one user, Chris Beach, tweeted on Friday. "They're handling claims MANUALLY. 72hrs wait."

In addition to the long wait, some users received non-working codes. That problem occurred because Apple's form to request a free copy of Mountain Lion went live two days before OS X 10.8's release. As a result, some users were able to get their code ahead of the operating system's launch, only to later find out that the code didn't work.

"Like everyone else, my original redemption code was falsely recognized as already used," one user with the moniker "bogus" wrote in a MacRumors forum post. "Sent an email to Apple Support last night, got a new redemption code this morning. Except when I redeemed the code, instead of automatically downloading Mountain Lion, it downloaded Mountain Lion Server."

An Apple spokesperson did not immediately respond when contacted about the problems. New Mac owners still have until 24 August to request a complimentary upgrade as part of the Up-to-Date program.

Meanwhile, those who aren't eligible for the free Mountain Lion upgrade have been paying £13.99 for new OS without issue. Since its Wednesday debut, the revamped OS has found its way to 3.2 per cent of all Macs, according to stats from mobile ad firm Chitika.