README.md

@@ -140,6 +140,18 @@ asyncio.run(main())
 
 The package exports `PrinterClient`, `connect`, `PrinterError`, `PrinterNotFound`, `PrinterTimeout`, `PrinterNotReady`, and `PrinterStatus`.
 
+## Troubleshooting
+
+### Classic Bluetooth: [Errno 12] Out of memory
+
+If you encounter `[Errno 12] Out of memory` failures on Classic Bluetooth connections, it typically implies a stale state in the BlueZ stack or the printer's radio. As of v0.1.17, the library automatically falls back to a BLE connection when this specific error occurs.
+
+If you wish to resolve the underlying Classic Bluetooth issue, these steps can help:
+
+- **Power cycle the printer**: This clears the printer's radio state and is often the only fix if the device is rejecting RFCOMM.
+- **Verify Pairing**: Classic Bluetooth (RFCOMM) requires the device to be paired and trusted in the OS. You can use the "Pair Device" or "Unpair Device" buttons in the Home Assistant add-on's web UI, or run `bluetoothctl pair <MAC>` and `bluetoothctl trust <MAC>` (or `bluetoothctl remove <MAC>`) on the host. Pairing is not required for BLE.
+- **Restart Bluetooth**: `systemctl restart bluetooth` on the host can clear stuck socket handles.
+
 ## TODO
 
 - [ ] Emoji support in text labels. The default Pillow font has no emoji glyphs, so they render as squares. Needs two-pass rendering: split text into emoji/non-emoji segments, render emoji with Apple Color Emoji (macOS) or Noto Color Emoji (Linux) using `embedded_color=True`, then composite onto the label.

fichero/printer.py

@@ -8,6 +8,7 @@ Device class: AiYinNormalDevice (LuckPrinter SDK)
 
 import asyncio
 import sys
+import errno
 from collections.abc import AsyncGenerator
 from contextlib import asynccontextmanager
 
@@ -427,14 +428,31 @@ async def connect(
                     yield pc
                     return
             except (PrinterError, PrinterTimeout) as exc:
+                # On Linux, a stale BlueZ device state can cause RFCOMM connect()
+                # to fail with [Errno 12] Out of memory. This is a known quirk.
+                # We treat this specific error as a signal to fall back to BLE.
+                if isinstance(exc.__cause__, OSError) and exc.__cause__.errno == errno.ENOMEM:
+                    print(
+                        "Classic Bluetooth connection failed with [Errno 12] Out of memory. "
+                        "Falling back to BLE connection."
+                    )
+                    classic = False  # Modify flag to trigger BLE path below
                     last_exc = exc
+                    break
+                last_exc = exc
+
+        # If the 'classic' flag is still true, it means the loop completed without
+        # hitting the ENOMEM fallback case, so all classic attempts failed.
+        if classic:
             if last_exc is not None:
                 raise PrinterError(
                     f"Classic Bluetooth connection failed for '{address}'. "
                     f"Tried channels: {channels}. Last error: {last_exc}"
                 ) from last_exc
             raise PrinterError(f"Classic Bluetooth connection failed for '{address}'.")
-    else:
+
+    # If classic=False initially, or if it was set to False for the ENOMEM fallback:
+    if not classic:
         target = await resolve_ble_target(address)
         def _is_retryable_ble_error(exc: Exception) -> bool:
             msg = str(exc).lower()