I get the error when I only do: #include <boost/thread.hpp> From: boost-users-bounces@lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Ovanes Markarian Sent: Monday, March 29, 2010 15:47 To: boost-users@lists.boost.org Subject: Re: [Boost-users] compiler error on using threads with boost On Mon, Mar 29, 2010 at 3:38 PM, Iskandar Prins <iprins@alphabay.nl<mailto:iprins@alphabay.nl>> wrote: Hi, I get this compiler error : boost/thread/future.hpp", line 414: Error: Formal argument other of type boost::unique_lock<boost::mutex> in call to boost::unique_lock<boost::mutex>::operator=(boost::unique_lock<boost::mutex>) has an inaccessible copy constructor. Any idea why this is? I'm using the sun compiler to compile it with Because unique_lock cannot be copied. Either pass it as reference or use shared_lock. Regards, Ovanes