Height mismatch between bitcoin-qt and bitcoin explorers I am running bitcoin-qt on the testnet. The count of the last block is 787794 which is way ahead of what I see on blockchain explorers such as https://test.webbtc.com/, which shows the last block as 787747. Why is there this difference ?
Apparently, there is a fork between 0.12.0 and 0.12.1 nodes.

Testnet is used to test new features of Bitcoin before they are released on the main network. Apparently, the newer version of Bitcoin created a block that was invalid under the rules of the older Bitcoin version. This caused the network to split, as the two versions now created two competing blocks at the same height, and are following separate chains.

Apparently, the softfork activation is being tested, which may cause your experience:

&lt;phantomcircuit&gt; nope
&lt;phantomcircuit&gt; like 50% of the hashing power currently on testnet randomly drops out for days at a time
&lt;phantomcircuit&gt; and im messing with the timestamps to get many many many more blocks than there should be
&lt;phantomcircuit&gt; the two things combined result in soft forks activating with way less than 95% of the hashing power