Bitcoin's supply is supposed to cap at 21 million coins. On August 15, 2010, that property was briefly false. An attacker exploited an integer-overflow bug in Bitcoin Core to mint 184.467 billion BTC across two outputs in a single transaction in block 74,638. Then Satoshi shipped a fix in 5 hours, the network forked back to a clean tip, and Bitcoin's most existential bug was resolved before most of the world even knew it had happened.
The bad block is still on chain in some forks of Bitcoin Core's testing data, but the canonical mainnet you're querying right now reflects the fixed history. What's still readable: block 74,638 itself on the orphaned side, and all the blocks since that have validated under the post-fix rules.
The state at block 74,637
Right before the bug, the network was healthy. Block 74,637 looked normal: transactions paying reasonable values, total subsidy at 50 BTC, all the usual.
Standard. Nothing remarkable.
What happened in block 74,638
On the original (now-orphaned) chain, block 74,638 contained a transaction with
two outputs each paying 92,233,720,368.54 BTC. That's 9.22 × 1010
bitcoin per output, more than 4,000 times the entire eventual supply. The bug:
Bitcoin Core's CTransaction::CheckTransaction verified that no single
output exceeded the maximum money limit, but didn't verify that the sum
of outputs didn't overflow a signed 64-bit integer. The attacker's two outputs
summed to a negative number when the math wrapped, which slipped past validation.
The current canonical chain replaced this block with a different one (height 74,638 on the post-fix chain). You can fetch its hash:
Subsidy: 50 BTC. Total outputs: a normal range. Nothing wrong. The damaged block at this height was orphaned by the patched-client majority.
The fix
Satoshi's response, in five hours, in commit d4c6b90c, added an explicit check: each output must be non-negative AND in range, AND the running sum must stay non-negative. The fix shipped as Bitcoin v0.3.10 the same day. Within hours, the patched chain overtook the buggy one, the bad block was orphaned, and the supply was restored to its honest curve.
Look at any block from then to now: subsidy plus fees, all clean.
The post-fix chain has been clean for 16 years. No output overflow, no inflation, no recurrence. The 21-million cap holds because it's been re-validated by every node, in every block, since.
The lesson
Bitcoin's first existential bug was caught and patched in five hours. That's not because the code was perfect, it wasn't, but because the network was small enough, and Satoshi engaged enough, to coordinate a soft fork in real time.
Today, with Bitcoin Core mature and the network global, fixes look different. But the property the patch enforced, no inflation, has held for 16 years and 800,000+ blocks since. The chain you're querying right now is structurally clean.
That's the trust you're paying for when you run your own node, or use one that does, like ours. Run the queries. Verify the math. The numbers add up.
Read more: The Genesis Block, 10,000 BTC for Two Pizzas, or The Halvings.