OctoPrint-AutoConnectPlus

Automatically (re)connect your printer in OctoPrint — not only over serial, but also through the OctoPrint 2.0 connector framework for Moonraker (Klipper), Bambu and any other registered connector.

AutoConnectPlus is a fork of OctoPrint-PortRetryPlus that keeps its proven retry/timer logic and extends it to the modern connector API.

How it works

OctoPrint can auto-connect once on startup, but it does not retry if that attempt fails, and it does not reconnect after a disconnect. On OctoPrint 2.0+ this applies to your preferred connection (the connector and its parameters); on OctoPrint 1.x it applies to the classic serial connection.

AutoConnectPlus fills exactly that gap on both — keeping a printer connected by retrying until it succeeds, and reconnecting automatically after any disconnect:

• A RepeatedTimer runs while the printer is disconnected and retries on a configurable interval.
• It reuses OctoPrint's own preferred connection — connector and parameters are read from printerConnection.preferred, so whatever you set up in OctoPrint's connection dialog (serial, Moonraker, Bambu, ...) is what gets reconnected. There is nothing to configure twice.
• For connector types it checks connection_preconditions_met and probes the host's TCP port before each attempt, so an offline printer is skipped quietly (the timer just keeps waiting) instead of flooding the log.
• When a connect is actually attempted but keeps failing, the retry rate backs off progressively, so a misconfigured connection doesn't hammer the log every interval.
• For serial it keeps the original PortRetryPlus behaviour, including the optional forced port when OctoPrint's serial port is unset or AUTO. Whether the port is present is checked without opening it — no DTR toggle, so boards that reset on serial open (Arduino-style) are not reset twice per attempt. Symlinked ports (/dev/serial/by-id/..., udev aliases) are resolved before matching.
• Event-driven: the retry timer starts on Disconnected and stops on Connected.

OctoPrint stores a single preferred connection, so there is never any ambiguity. If it is missing or incomplete (or the matching connector plugin is not installed), the plugin simply keeps waiting and logs the reason once instead of every interval.

Requirements

• Serial mode works on any reasonably recent OctoPrint (1.x included), where it behaves like classic PortRetryPlus.
• Moonraker / Bambu (and other connectors) require OctoPrint 2.0+ (the connector framework) and the matching connector plugin installed:
  • OctoPrint-MoonrakerConnector
  • OctoPrint-BambuConnector (which provides the bpm / bambu-printer-manager dependency — AutoConnectPlus does not install it itself).

Installation

Install via the OctoPrint Plugin Manager using a URL.

Latest release (recommended) — always points at the newest release, which may be a prerelease (e.g. an -rc) until the first stable version is out:

https://github.com/ajimaru/OctoPrint-AutoConnectPlus/releases/download/latest/OctoPrint-AutoConnectPlus-latest.zip

Configuration

First set up and connect your printer once via OctoPrint's normal connection dialog (serial / Moonraker / Bambu / ...). AutoConnectPlus will then reconnect using exactly that connection.

Open Settings → AutoConnectPlus. It shows the detected connection (type and target, refreshed every time the dialog opens) and these options:

• Enable automatic (re)connect — master switch, on by default. When off, the plugin stays idle and never reconnects.
• Retry interval (seconds) — how often to attempt a reconnect while disconnected.
• Forced serial port — serial only, optional. Used only when OctoPrint's serial port is unset or AUTO.

The printer profile used is OctoPrint's default profile.

The same options can be set in ~/.octoprint/config.yaml:

plugins:
  autoconnectplus:
    enabled: true          # master switch
    interval: 5.0          # seconds between retries (minimum 0.1)
    forced_port: ""        # serial only: used when OctoPrint's port is unset/AUTO

Troubleshooting

All plugin activity is logged to octoprint.log, prefixed with octoprint.plugins.autoconnectplus.

• Nothing reconnects at all — check that the plugin is enabled in its settings and that the detected connection shown there is the one you expect. If a warning is shown instead (no port detected, no preferred connection stored, connector plugin missing), fix that first: connect once via OctoPrint's connection dialog and/or install the matching connector plugin.
• The printer is off and the log stays quiet — that is intentional. While the printer's host or serial port is unreachable, the plugin waits silently (details only appear at DEBUG log level) and connects as soon as it comes back.
• Retries seem to slow down — also intentional. Every failed connect attempt backs the retry off by one more interval, capped at 15 intervals (~80 s with the default 5 s interval). A successful connect resets the backoff. Persistent problems (e.g. a missing connector plugin) are logged once at error level, then silently retried.
• Serial port never resolves — if OctoPrint's serial port is AUTO and the port cannot be detected, set a forced serial port in the plugin settings or a concrete port in OctoPrint's connection dialog.

Development

git clone https://github.com/ajimaru/OctoPrint-AutoConnectPlus.git
cd OctoPrint-AutoConnectPlus
python -m venv .venv && source .venv/bin/activate
pip install "OctoPrint>=1.11" -e ".[dev]"

pytest             # run the unit tests
ruff check .       # lint

The tests mock OctoPrint's printer and the connector framework, so they run against both OctoPrint 1.x and 2.x installs; CI covers both generations.

Translations use the standard OctoPrint babel workflow (see translations/README.txt). UI strings live in the settings template; if you change them, update translations/messages.pot and the existing languages.

Releases: bump version in pyproject.toml (single source of truth — the plugin reads it from package metadata at runtime), then push a matching tag such as v0.2.0. The release workflow verifies tag and version match, smoke-tests the wheel against OctoPrint 1.x and 2.x, publishes the GitHub release and updates the rolling latest release behind the stable install URL above.

Credits

• Original OctoPrint-PortRetryPlus by hprombex.
• Earlier work and inspiration credited to vehystrix.

License

Licensed under the GNU Affero General Public License v3 or later (AGPL-3.0-or-later), matching the original project. See LICENSE.

Note

About this project. I built this for my own printer setup with AI, and if it helps others, even better. I have tested it to the best of my knowledge and ability. Disclosed here per the OctoPrint plugin guidelines. Issues and PRs are welcome.