Michael wrote:

boost::dynamic_bitset<byte> m_patterndelta;

// intialization of m_patterndelta

....

std::vector<byte> pack;

boost::to_block_range<byte>(m_patterndelta, pack.begin()); // GPF because of bad pointer in "pack". Cannot figure why, may be someone can help?

How about trying: boost::to_block_range<byte>(m_patterndelta, back_inserter(pack)); you're trying to write to pack's elements, which are none at the point of the call. HTH Pablo Aguilar