qBittorrent/libtorrent Moving Towards BitTorrent v2
Posted: 25 Sep 2026 13:32
With the release of libtorrent-2.1, we intend to discontinue support for libtorrent-2.0 in the upcoming qBittorrent 5.3.
And since it is supposed to be free from the main disadvantages of libtorrent-2.0, namely the disadvantages of the disk I/O subsystem, which caused us to support the legacy libtorrent-1.2 all this time, we intend to discontinue its support too (probably later).
qBittorrent 5.3.x will probably still support them at the code level, and their support will be permanently removed in a subsequent branch.
EDIT for clarification:
Official builds will be based on libtorrent 2.1 and 1.2.
The default official build will use libtorrent 2.1 (now it is 1.2).
The source code will be compatible with 1.2, 2.0 and 2.1. The support for 1.2 and 2.0 will be marked as deprecated.
On the next-next major version (aka qbittorrent 5.4.x) the deprecated version will be dropped/removed.
In the unlikely scenario that 2.1 doesn't fix the disk I/O problems of 2.0 we will consider of undeprecating 1.2.
I think now is a good time for I2PSnark and Postman Tracker to start supporting the BitTorrent v2 protocol. The timing seems right, and development can happen simultaneously. Any wrinkles or issues specific to torrenting over I2P with BitTorrent v2 can then be identified and ironed out along the way.
qBittorrent issue = https://github.com/qbittorrent/qBittorrent/issues/24689
First Beta release = https://github.com/qbittorrent/qBittorr ... 5.3.0beta1
And since it is supposed to be free from the main disadvantages of libtorrent-2.0, namely the disadvantages of the disk I/O subsystem, which caused us to support the legacy libtorrent-1.2 all this time, we intend to discontinue its support too (probably later).
qBittorrent 5.3.x will probably still support them at the code level, and their support will be permanently removed in a subsequent branch.
EDIT for clarification:
Official builds will be based on libtorrent 2.1 and 1.2.
The default official build will use libtorrent 2.1 (now it is 1.2).
The source code will be compatible with 1.2, 2.0 and 2.1. The support for 1.2 and 2.0 will be marked as deprecated.
On the next-next major version (aka qbittorrent 5.4.x) the deprecated version will be dropped/removed.
In the unlikely scenario that 2.1 doesn't fix the disk I/O problems of 2.0 we will consider of undeprecating 1.2.
I think now is a good time for I2PSnark and Postman Tracker to start supporting the BitTorrent v2 protocol. The timing seems right, and development can happen simultaneously. Any wrinkles or issues specific to torrenting over I2P with BitTorrent v2 can then be identified and ironed out along the way.
qBittorrent issue = https://github.com/qbittorrent/qBittorrent/issues/24689
First Beta release = https://github.com/qbittorrent/qBittorr ... 5.3.0beta1