Bitcoin​ Unlimited has been facing some issues with the number of functioning nodes dropping time and again. In March, the number fell to 410 to eventually recover. Although milder but similar trend has been witnessed through the month, with a massive one on April 22, 2017 with the number of operating nodes plummeting to 223.

A full node is defined as “a program that fully validates transactions and blocks. Almost all full nodes also help the network by accepting transactions and blocks from other full nodes, validating those transactions and blocks, and then relaying them to further full nodes.”

Graph of the number of operating Bitcoin Unlimited nodes, highlighting the drops in March and April

These constant attacks are a setback to the highly-debated plan - Bitcoin Unlimited –to resolve Bitcoin’s scaling issue. Bitcoin Unlimited is being promoted by some of the biggest miners of the Bitcoin community.

The issue relates to the problem of congestion on the Bitcoin network. It started garnering attention when Bitcoin transactions took more time than usual. Bitcoin is rising in popularity and attracting new users to its network, thus making it crowded and resulting in the delays.

Bitcoin blocks comes with a pre-programmed capacity of 1MB under the current popular system of Bitcoin Core. However, Bitcoin Unlimited want this restriction of 1MB to be removed as a solution to the congestion on the network.

Bitcoin Unlimited advocates complete freedom and flexibility to increase the size of blockchain​ and this will be done by miners. So, if there is a consensus on this, we will have a new bitcoin blockchain with large-sized blocks.

Opponents feel that increasing the size of blocks can result in a hard fork in the code which would split the network. They also believe that such flexibility can result in miners opting for bigger and bigger blocks – making it harder for miners with limited resources to mine, thereby concentrating the ‘mining power’ in the hands of few miners. Such concentration will essentially result in centralization which is opposite to the idea of decentralization which is core to Bitcoin.

Some of the proposals other than Bitcoin Unlimited include Segregated Witness, BIP 100, 8MB Blocks. The mining pool support by proposal shows that Bitcoin Unlimited has about 40% support, followed by SegWit at 34% while the rest support BIP100 and 8MB Blocks.

While the price of bitcoin (for now) shrugged off the attack on Bitcoin Unlimited nodes. The divide within the Bitcoin community on the issue of scalability does pose a threat.