Editing Openai/692da612-aac4-800b-80dd-f1568632e2ff (section)

=== Assistant: Good — you’ve confirmed the sketch compiles and the error happens only at upload. ===
Good — you’ve confirmed the sketch compiles and the error happens only at upload. That means the Arduino / bootloader is probably fine and the problem is Windows / COM port access. Below I’ll give a short, ordered checklist with exact actions to try (do them in order). Follow each item and try uploading after the step that mentions “Try upload now.”

==== - Completely close Arduino IDE first. ====
* Close any terminal apps (PuTTY, Tera Term), VS Code, PlatformIO, Python scripts, Serial Monitor windows.
* Open Task Manager → Processes → look for python.exe, putty.exe, node, Code.exe etc. Right-click → End task for anything that might open serial ports.

Try upload now.

==== - Right-click Arduino IDE → Run as administrator → open your sketch → Tools → Port → choose COM6 (Arduino Uno) → Upload. ====

Try upload now.

==== - Unplug UNO → change to a different physical USB port on the PC (prefer rear ports). ====
* Use a different USB cable (must be data cable).
* Re-plug UNO. Wait ~5s for drivers to re-initialize.
* Confirm Device Manager → Ports (COM & LPT) shows Arduino Uno (COM6). If COM changed, select that port in Arduino IDE.

Try upload now.

==== Windows doesn’t show this directly. Use Process Explorer (Sysinternals) or handle.exe: ====

Process Explorer method (recommended)
# Download & run Process Explorer from Microsoft Sysinternals.
# Press Ctrl+F (Find) → type COM6 → it will list the process holding a handle to COM6.
# If a process is listed, select it in Process Explorer → right-click → Kill Process.

handle.exe method
# Download handle.exe from Sysinternals.
# Open Command Prompt as Administrator and run:

<syntaxhighlight>handle.exe -a COM6

</syntaxhighlight>

It will list process IDs using COM6. Kill the processes (Task Manager).

Try upload now.

==== 1. Open Device Manager → Ports (COM & LPT). ====
# Right-click the Arduino device (COM6) → Uninstall device.
# If there’s a checkbox Delete the driver software for this device, check it.
# Unplug Arduino, wait 3–5s, plug it back in. Windows will reinstall drivers.

Try upload now.

==== 1. Device Manager → Ports → Right-click Arduino → Properties → Port Settings → Advanced... ====
# In COM Port Number select an unused port (e.g., COM3 or COM4). Click OK.
# Select that new port in Arduino IDE → Tools → Port.

Try upload now.

==== - If Device Manager shows CH340 or USB-SERIAL, reinstall the correct driver: - Uninstall device (see step 5) and choose Delete driver software if available. - Reboot PC and let Windows reinstall, or install the vendor driver (CH340/CP2102). (I can give exact driver links if you want.) ====

Try upload now.

==== 1. Power OFF Arduino. Place a jumper between TX (pin1) and RX (pin0). ====
# Power ON Arduino. Open Serial Monitor on the COM shown in Device Manager at 9600.
# Type something — if you see it echoed back, the USB-serial interface is OK.
# Remove jumper afterwards.
* If loopback fails, problem is with the USB-serial chip/driver/cable.

==== - When you press Upload, watch the RX/TX LEDs: if they do not flash at all, the PC is not talking to the board. That points to driver/COM lock/cable problems. ====
* If they flash during upload but upload still fails, note exact behavior and tell me.

==== - Try the UNO on another PC — if it uploads there, the problem is on your Windows machine. ====
* If you have another UNO, try uploading to that board to isolate the hardware.

===== - After trying steps above, tell me the first step that changed behavior (e.g., “Process Explorer showed python.exe holding COM6 and killing it fixed upload”, or “Loopback test failed”, or “No change after all steps”). =====
* If Device Manager shows the device name under Ports, paste the exact text shown (e.g., Arduino Uno (COM6) or USB-SERIAL CH340 (COM6)).

If you want, I can give step-by-step for Process Explorer or driver reinstall with exact clicks — tell me which one you want and I’ll write the exact steps.