Just hours after the release of an alternative implementation of the bitcoin software, a group of miners, exchanges and service providers who work with the digital currency issued a letter stating that they would not back any “controversial” changes to the bitcoin network.

The letter calls for an increase in the cap that currently limits the bitcoin blockchain’s transaction processing capabilities while also voicing support for a proposal called Segregated Witness, code previously put forward by the team behind the majority-used Bitcoin Core software as part of a broader scalability roadmap.

Those signing the letter said they reject the viability of a “contentious hard-fork”, a change to the bitcoin software that makes previous versions incompatible. In this instance, all of the network’s users would either have to download new software in order to be part of the new chain, or transaction history, or continue running the old version.

In the case of Bitcoin Classic, the change could result in one network operating with blocks with a 2MB block size cap and another with the existing 1 MB cap.

The letter reads:

“We think any contentious hard fork contains additional risks and potentially may result in two incompatible blockchain versions, if improperly implemented. To avoid potential losses for all bitcoin users, we need to minimize the risks. It is our firm belief that a contentious hard-fork right now would be extremely detrimental to the bitcoin ecosystem.”

The publication followed the release of Bitcoin Classic, an effort to raise the block size limit of the bitcoin network by means of a hard fork. Prior to the release of the client, those backing the project claimed significant support from the bitcoin mining community, going as far as listing a number of mining entities on the project’s main website.

Yet, doubts remained as to the level of support from miners (particularly those based in China) for the Bitcoin Classic proposal.

The letter’s signatories include mining entities BitFury, BW.com, BTCC, F2Pool and GHash.IO, a list that constitutes close to 70% of the bitcoin’s hash rate distribution, according to data from Blockchain.info.

Most notably, the letter states that signatories would not run production-grade versions, nor would they mine blocks as part of a hard fork of the bitcoin network, naming Bitcoin Classic and Bitcoin XT, an earlier proposal to hard fork the network, specifically.

The letter explains:

“We are as a matter of principle against unduly rushed or controversial hard-forks irrespective of the team proposing and we will not run such code on production systems nor mine any block from that hard-fork. We urge everyone to act rationally and hold off on making any decision to run a contentious hard-fork (Classic/XT or any other).”

Those signing the letter also called for greater collaboration with the team behind Bitcoin Core, though the wording notably does not preclude those involved from running test versions of the Bitcoin Classic network.

“In the next three weeks, we need the Bitcoin Core developers to work with us and clarify the roadmap with respect to a future hard-fork which includes an increase of the block size,” the letter states. “Currently we are in discussions to determine the next best steps.”

A full list of signatories can be found here.

Log splitting visualization via Shutterstock