TON Mainnet Incident Postmortem: July 13, 2026

On July 13 at 09:00 UTC, the team started a scheduled mainnet benchmark. The test generated modified jetton transfers to split the network into 16 shardchains and evaluate network behavior under multi-shard load.

The same benchmark had previously completed successfully in testnet and local environments.

At approximately 09:30 UTC, after mainnet expanded beyond four shardchains, the shardchain block rate dropped significantly and user message processing was affected. The masterchain remained stable.

The benchmark was stopped, and the network recovered automatically by approximately 11:12 UTC.

Root cause

The investigation found that, with four or more shardchains, inter-validator traffic on the current software version and mainnet structure exceeded 1 Gbit/s—the current recommended network capacity for validators.

Remediation

• A validator vote temporarily reduced the maximum number of shardchains from 16 to 4. At four shardchains, network traffic remains within the current limits.
• Upcoming releases introduce Plumtree broadcasts, expected to reduce inbound node traffic by approximately 4× and outbound traffic by 2× after activation.
• The recommended minimum validator network capacity will be increased to 10 Gbit/s.