---
title: "Some Miners Generating Invalid Blocks"
alias: "spv-mining"
active: true
banner: "WARNING: many wallets currently vulnerable to double spends (click here to read)"
---

<p><em>This document is being updated as new information arrives.  Last
update: 2015-07-04 06:00 UTC</em></p>

<h2 id="summary">Summary</h2>

<p>Some miners are currently generating invalid blocks. <b>Bitcoin Core
   0.9.4 and earlier</b> will accept these invalid blocks, making them
   more vulnerable to double spends.  This <b>also applies to web wallets</b>
   from companies that still use 0.9.4 or earlier nodes.</p>

<p><b>Lightweight (SPV) wallets are also at increased risk,</b> and will
      remain so until all miners have switched back to full
      validation.</p>

<p>Users of the above listed vulnerable software must either <b>stop
   accepting transactions—even if they are confirmed—</b> or <a href="/en/download">upgrade to Bitcoin
   Core 0.10.2</a>.</p>

<p>Users of Bitcoin Core 0.9.5 and later are currently unaffected.</p>

<p><b>Miners:</b> If you are a pool miner, please switch immediately to a
   pool to that fully validates blocks.</p>

<p><b>More information to follow.</b></p>

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