Restart Detector
by enjarai
Restart Detector, a Fabric mod, adds a block that sends a redstone signal to warn sensitive contraptions before the server stops or restarts.
What it does
The detector block outputs a redstone signal that rises slowly from 1 toward 15 as shutdown approaches, then drops back toward 0 after the server comes back online. That gives flying machines, pistons and other moving contraptions time to halt and avoid breakage, and gives the world time to load before they start again. The block uses a daylight-sensor model and sits on the server, so players join without installing anything, though Fabric API and Polymer, which is bundled inside the mod, are needed on the server.
By default the mod hijacks the vanilla stop command and adds a countdown before the server shuts down. The countdown length is set by stopCountdownTicks, with 600 ticks (30 seconds) as the default. Server owners can disable the hijack with hijackStopCommand, and a few subcommands manage how the countdown and the detectors behave. Config changes take effect only after the server is restarted.
Key features
Redstone shutdown warning
Detectors output a signal that climbs toward 15 during the countdown, so attached redstone can react before the stop.
Configurable stop countdown
The vanilla stop command waits a set number of ticks before shutting down, with the default at 600 ticks.
Stop and cancel subcommands
Subcommands cancel a stop or bypass its countdown, letting operators control the shutdown directly.
Restart signal decay
After the server returns, the detector's output slowly decays back to 0 so the world can finish loading first.
Gallery
Compatibility
Latest build for each game version and loader.
26.x5 of 5 versions with builds
1.21.x12 of 12 versions with builds
1.20.x7 of 7 versions with builds
1.19.x1 of 1 version with builds
Only full game releases are shown. This mod publishes no snapshot builds.
Requirements
Dependencies declared by the latest file for each loader.
Required 1
Embedded 1
Use cases
Who it’s for: Server owners who run redstone contraptions, flying machines or farms that break when the server stops, and who want a timed warning before each restart.
How it compares
Classic Detector is a Fabric mod for 1.20 – 1.21.4 that is client-side only and not open source under the MIT License, so it does nothing on a server. More Detectors is a Fabric mod for 1.20.4 with a Creative Commons Attribution Share Alike 4.0 license and needs both sides. SensiCraft is open source under the MIT License, for 26.2, and runs on client and server.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Restart Detector | Fabric | 1.19.4 – 26.3 | Server-side only | 2026-10-10 |
| Classic Detector | Fabric | 1.20 – 1.21.4 | Client-side only | 2025-04-17 |
| More Detectors | Fabric | 1.20.4 | Client and server | 2024-05-17 |
| SensiCraft | Fabric | 26.2 | Client and server | 2026-10-14 |
Questions
Does Restart Detector need to be installed on the client?
How does a server owner change the countdown length?
Can the stop command countdown be turned off?
In the catalog
Restart Detector is one of 8,499 Technology mods on ModsFinder, and one of 4,201 Technology mods for Fabric. 8,071 mods support Minecraft 26.3.
More from enjarai
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What the author says
This fully server-side mod adds Restart Detectors, a new block that will output a redstone signal before server shutdowns. These new blocks can be used to disable sensitive redstone contraptions to prevent expensive breakages, and can even be used on flying machines due to their lightweight design™! (no blockentity…
Official listing
- Modrinth page
- modrinth.com/mod/restart-detector
- Owner
- enjarai
- Published
- 2023-11-07
- Updated on Modrinth
- 2026-10-10
- Facts verified
- 2026-10-15