The printer cannot find the firmware update on the card or USB drive
Guide based on the manufacturers' official documentation; usi3d has not yet verified it on a machine.
Technology: FDM · Symptoms: Does not read the SD card or USB drive, Problems after a firmware update · Updated on 10 October 2026
Symptom
You have copied the new firmware to the microSD card or USB drive, but the printer does not offer to update, cannot find it, or the update stops halfway.
Likely causes, from most to least likely
- The file is not where the printer looks for it: Prusa and Bambu Lab want it in the drive's root, and Elegoo, on the Neptune 4, wants the ELEGOO_UPDATE_DIR folder copied as it is.
- A file renamed or extracted when it should not be: Bambu Lab warns that the update then fails. Each brand wants it its own way: Prusa, for example, asks you to take the «.bbf» file out of its package.
- Leftovers from another update on the drive: Prusa asks that there be no previous firmware on it.
- A drive the printer does not support: Elegoo asks for a drive of under 32 GB, formatted and empty, for the Neptune 4.
- A starting version that is too old or the same as the new one: Bambu Lab requires at least 01.07.00.00 on the P1P and P1S to update offline, and Prusa only offers versions newer than the one you have.
- A power cut or the drive removed during the update: Bambu Lab asks you not to switch off the printer and to wait 10-20 minutes.
Checks to tell which one it is
- Check that the firmware is exactly for your printer model and that you downloaded it from the maker's website.
- Check on the computer where the file is: in the root or inside a folder.
- Compare the file's name and type with what your maker's guide says.
- Check on the printer's screen which version you have now.
Before you start
Before taking anything apart, cleaning or adjusting it, switch the printer off and unplug it, unless a step says otherwise, and do not touch the nozzle, the heater block or the bed until they have cooled down. If in any doubt about electricity, heat or moving parts, stop and ask a professional.
Step-by-step fix
Download the right firmware
Download the firmware from the maker's website, from the page for your exact model: Prusa, for example, has a different firmware for each model and variant (MK4, MK4S, CORE One, CORE One+…).
Check: You have the file for your model and the version you want to install.
If that does not fix it: Prepare the drive (next step).
Prepare the card or drive
Use a drive your printer supports (Elegoo: under 32 GB for the Neptune 4), formatted and with no previous firmware (Prusa, Elegoo). Copy the file to the root and eject the drive from the computer before removing it.
Check: Only the new firmware is on the drive, in the root.
If that does not fix it: Copy it the way your maker asks (next step).
Copy it the way your maker asks
Bambu Lab: the package, not renamed or extracted, in the root, then Settings, Firmware, Update Offline. Prusa: the «.bbf» file in the root; when you press the reset button, the printer compares versions and offers «FLASH» if the file is newer. Elegoo, Neptune 4: the whole ELEGOO_UPDATE_DIR folder and, in Settings, Info, the upload icon.
Check: The printer offers to install the new version.
If that does not fix it: If it does not, check the starting version (next step).
If it is not offered because of the version
Prusa only offers versions newer than the installed one: to reinstall the same one or downgrade there is a separate guide. Bambu Lab requires at least 01.07.00.00 on the P1P and P1S to update offline; if you are below that, update online first.
Check: You know which version you can install from the drive.
If that does not fix it: Follow your maker's guide to downgrade or reinstall the version.
Do not interrupt the update
During the update, do not switch off the printer or remove the drive: Bambu Lab asks you to wait 10-20 minutes, and the printer restarts by itself when it finishes.
Check: The screen shows the new version.
If that does not fix it: If it stopped halfway, repeat the update from the drive.
After updating
Check the version on the screen and recalibrate whatever your maker asks for: Elegoo asks you to level the Neptune 4 again and adjust the Z offset after updating.
Check: The first test print comes out fine.
If that does not fix it: If something goes wrong after updating, follow the guide for problems after a firmware update.
Prevention
- Use a formatted, empty drive for firmware.
- Never switch off the printer during an update.
- Read your model's guide before updating: each brand does it differently.
Still not fixed?
Tell usi3d's AI about your case: choose your printer, describe what you see and add photos if you like. It proposes checks step by step, with their sources.
Printers it applies to
Any FDM (filament) 3D printer, from any brand.
Official sources
This guide summarises the official documentation linked here:
This guide is general information: usi3d has summarised it from the official documentation linked here, and it may not match your model, its version or its firmware. If in doubt, follow the manual and the support of your printer's manufacturer. You decide what you do with your machine, and working on it may affect its warranty.