Troubleshoot a dot-matrix printing problem

If printing doesn’t work on the first try, don’t worry: the most common causes are simple to identify and fixed in a few minutes. Two commands cover almost every situation.

First reflex: `status`

Before anything else, ask the machine for its state. A single command tells you whether the machine is paired, whether the agent is running, and which printers it sees.

Open a Command Prompt (Windows key → type cmd → Enter), then:

cd "C:\Program Files\SynkriaOps"
synkriaops-print status

The result points you straight to the answer:

What `status` shows	What to do
Pairing: MISSING	The machine is not linked to your account. See Install the agent.
Agent: stopped (or not installed)	See “The machine appears offline” below.
Printers: none detected	The printer is not installed in Windows, or it is switched off.
A printer whose name starts with `\\`	Printer shared by another PC: see “The agent can’t see my printer”.
Everything OK, but nothing comes out of the tray	Move on to the diagnostic below.

The diagnostic: pinpoint the cause in a minute

If the machine is online but the paper stays blank, the diag command prints 4 numbered test blocks, from the simplest (raw text) to the most complete. What you see come out tells you where the problem is.

Get the exact name of your printers (to avoid typos):
```
synkriaops-print printers
```
Run the diagnostic on the printer to test (copy the name exactly):
```
synkriaops-print diag --printer "EPSON LX-350 RAW"
```
Look at what physically comes out of the tray.

Interpreting the result

What comes out	What it means	What to do
Block 1 comes out readable (raw text)	The printer, the driver and the agent work.	✅ You are ready to print.
Block 1 stays blank (or nothing comes out)	The problem is the driver or the printer.	See “Nothing prints” below.
The paper advances but everything is blank	Data arrives, but nothing marks the paper.	See “A blank page comes out” — most often, the ribbon.
Block 3 comes out but the accents are wrong	Only the character table is misconfigured.	Set the printer to PC850 / Multilingual.

Common situations and fixes

Nothing prints, no error

Most often it’s the printer’s driver that’s at fault: a modern graphical driver doesn’t route raw data correctly. Fix: print through a “Generic / Text Only” queue, as described on the Choose & set up your printer page.

A blank page comes out (the paper advances)

The paper advances but stays blank. Check, in order:

The ribbon — dry, empty or badly seated (common on a rarely used printer). To settle it, run the printer’s self-test: switch it off, hold the LF/FF button down, then switch it back on. If the self-test also comes out blank, replace the ribbon and check the paper thickness lever (position closest to the platen).
The Cont. Feed - No Break = Not Available setting has not been made (see the configuration).
The printer is in IBM emulation instead of ESC/P.

Printing skips 2 or 3 pages

The text comes out, but the printer advances several sheets at each print: it’s a page length setting. Adjust the “Paper height (mm)” field in Settings → Invoicing → Templates so it matches the actual height of your sheet (140 mm by default).

“printer not found”

The name provided does not exactly match a Windows printer. Run synkriaops-print printers again and copy the name character for character.

The invoice comes out, but badly positioned

The text prints but the alignment on the multi-part paper isn’t perfect: adjust the dimensions and margins in your invoice template (Settings → Invoicing → Templates), in particular the paper width and height.

The agent can’t see my printer

You can see the printer in Windows, but synkriaops-print status doesn’t list it — or its name starts with \\ (for example \\POS-PC\EPSON).

This is the sign of a printer added as a network share from another PC. This type of printer belongs to the Windows session of the user who added it, whereas the agent runs at the machine level: it therefore cannot reach it.

Fix: install the printer as a local printer on this machine — Add a printer → USB or TCP/IP port (the printer’s IP address) — then run, in an administrator Command Prompt:

cd "C:\Program Files\SynkriaOps"
synkriaops-print install

The machine appears “offline”

The machine appears “Online” then falls back to “Offline”.

Good news: there is nothing to fix by hand. The agent restarts on its own in case of an incident, and a watchdog checks every 5 minutes that it is running. A machine that is durably offline therefore almost always points to an external cause.

Check in this order:

Is the PC switched on? This is the first cause, by far.
Does the internet connection work on this machine? Open a web page to make sure.
Take stock with status:
```
cd "C:\Program Files\SynkriaOps"
synkriaops-print status
```
- “Pairing: MISSING” or a “Machine revoked” message → the machine was disconnected on the app side. Generate a new code in SynkriaOps → Settings → Printing → Pair a machine, then re-pair (see below).
- Agent stopped / not installed → run the install again from an administrator Command Prompt: synkriaops-print install.
Is the printer switched on and loaded with paper?

Re-pair a revoked machine

In an administrator Command Prompt:

cd "C:\Program Files\SynkriaOps"
synkriaops-print pair --code XXXX-XXXX
synkriaops-print install

An invoice finds no machine (“no machine configured”)

Automatic printing only routes an invoice if there is a single active machine. If old test machines are still listed, the app doesn’t know which one to choose.

Fix: in Settings → Printing, disconnect all machines except the one that is “Online” (your current PC). The goal: a single active machine.

Consult the agent’s log

The agent keeps a timestamped log of its activity (jobs received, printed, errors). To open it, paste this path into the Windows Explorer address bar:

%LOCALAPPDATA%\SynkriaOpsPrint\agent.log