Restart the printer and run the update again from its own screen, which is Bambu Lab's first documented fix. If it stalls again, the cause is usually the network, the microSD card, a loose toolhead or AMS cable, or firmware too old to jump to the latest, and the offline update from a card or USB drive is the fallback.
Restart the printer and start the update again from its own screen, the first fix in Bambu Lab’s guides and error messages for the A1, P1, X1, H2 and P2S. If it fails again, fix the network, check the microSD card and reseat the toolhead and AMS cables before installing the update offline from a microSD card or USB drive. Bambu Lab warns against cutting power mid-update, so leave the printer on while the percentage still moves.
Why is my Bambu Lab firmware update stuck?
A Bambu Lab firmware update usually sticks because the download failed or the printer could not pass the package to one of its boards. Bambu Lab lists a weak or blocked network, a full or damaged microSD card, a loose toolhead or AMS cable, firmware too old to jump straight to the latest, and failed circuit boards.
After the download, the printer’s mainboard pushes the firmware to the toolhead (TH) board and to the AMS or AMS lite mainboard, so the stall can start at any of those three points.
| Cause Bambu Lab lists |
A1 and A1 mini |
P1 series |
X1 series |
| Network problem or full microSD card |
Yes |
Yes |
Yes |
| Toolhead cable not seated |
USB-C, TH board to mainboard |
Toolhead cable, TH board to MC board |
USB-C, TH board to AP board |
| AMS cable not seated |
Not listed |
Yes |
Yes |
| Firmware too old for a direct update |
Yes |
Yes |
Not listed |
| Replacement TH board with a mismatched hardware version |
Yes |
Not listed |
Not listed |
| Failed board |
Mainboard, TH board |
AP, MC and TH boards |
AP, MC and TH boards |
The H2 and P2S guides list no causes, only restart, retry and contact support.
Why does a Bambu firmware update get stuck at 32 percent?
Bambu Lab’s P1 update guide puts early stalls down to the network: “If the firmware update fails before the 50%, it’s usually a problem related to the network.” Bambu Lab gives no meaning for 32 percent or any other figure; its X1 page lists 0%, 34% and 97% only as examples of where updates stop.
On Bambu Lab’s forum, owners report 32 percent stalls on an A1, an A1 mini and a P1S. The P1S had failed from both Bambu Studio and the Android app, then went through when started from the printer’s own screen. The A1 owner, whose update failed “@ 31/32%” on the way to 01.03.00.00, got through by installing 01.02.02.00 first.
How long does a Bambu Lab firmware update take?
Bambu Lab says a Wi-Fi update takes 5 to 15 minutes on a P1 series printer, depending on network speed, and “a few minutes” on H2 and P2S printers. Offline updates take longer: about 20 minutes on the A1, A1 mini and P1, about 30 on the X1, and 20 to 30 on the H2, P2S and X2D.
| Printer (alphabetical) |
Wi-Fi update |
Offline, whole process |
Offline, install step |
Offline media |
| A1, A1 mini |
Not stated |
About 20 minutes |
10 to 20 minutes |
microSD card |
| H2 series (H2D, H2S, H2C, H2D Pro) |
“A few minutes” |
Not stated |
20 to 30 minutes |
USB drive |
| P1 series (P1P, P1S) |
5 to 15 minutes |
About 20 minutes |
10 to 20 minutes |
microSD card |
| P2S |
“A few minutes” |
Not stated |
20 to 30 minutes |
USB drive |
| X1, X1 Carbon |
Not stated |
About 30 minutes |
10 to 20 minutes |
microSD card |
| X2D |
Not stated |
Not stated |
20 to 30 minutes |
USB drive |
The A1 and P1 offline guides also give “about 5-10 minutes” for the install step; plan for their longer 10 to 20 minute figure.
Bambu Lab sets no point at which a frozen update counts as stuck. The longest time it quotes for any update is 30 minutes; if the percentage has sat frozen with no message for longer, restart and retry. An “Update Failed” screen has already given up and asks you to restart and update again.
After a successful update, Bambu Lab’s P1 guide says to power off for 5 seconds, power on and run a full calibration.
How do you fix a failed Bambu Lab firmware update?
To fix a failed Bambu Lab firmware update, restart the printer and retry the update from its own screen. If that fails, move the printer to a strong 2.4 GHz network or phone hotspot, format the microSD card and reseat the toolhead and AMS cables. Then install the offline package from a microSD card or USB drive.
Retry the update after each step below; Bambu Lab’s P1 and X1 pages say the order is flexible.
How to fix a stuck Bambu Lab firmware update, step by step
- Let a running update finish. Leave the power on while the percentage moves. Give it the time listed for your printer in the table above.
- Restart and retry from the printer’s screen. Turn the printer off and on, then start the update from the prompt or Settings > Firmware (Setting > General > Firmware Version on the X1). This is how the forum P1S owner above got past 32%.
- Fix the network. Move the printer closer to the router or join it to a 2.4 GHz phone hotspot. For “Time synchronization failed” (HMS_0500-0200-0002-0008), Bambu Lab says to set a public DNS server such as 8.8.8.8 or 1.1.1.1 on the router. A Pi-hole, firewall or VPN must let the printer reach NTP on port 123 and the domains Bambu Lab lists for firmware downloads:
*.bambulab.com and *.amazonaws.com. Bambu Lab’s list also includes a factory reset followed by a restart.
- Check the microSD card. A full card stops the download. Back up anything you need, then format the card in the printer and retry; Bambu Lab says the printer reads FAT32 only. On the P1 series, a card pulled while the printer runs can be corrupted, and Bambu Lab says replacing it fixes update failures.
- Reseat the toolhead and AMS cables. With the printer off and unplugged, reseat the toolhead cable listed for your printer in the table above. On the P1 and X1, also reseat the cables from the AMS through the buffer to the printer. On the P1 series, add the MC-AP cable between the AP and MC boards.
- Update without the AMS, then with it. For the P1 and X1, Bambu Lab says to disconnect the AMS and update the printer, then reconnect the AMS and update again. If the printer updates but the AMS does not, Bambu Lab suspects the AMS connection or a broken AMS mainboard.
- Install the update offline. Load the package from a microSD card or USB drive (steps below), which skips the cloud download.
- Open a ticket with logs. If nothing works, Bambu Lab suspects a failed board or cable. Submit a technical ticket and upload the printer logs from Bambu Handy (Me > Support Center) or Bambu Lab’s website.
A printer that will not boot after a failed update is past these steps and needs Bambu Lab support, starting with a technical ticket.
The offline update, in brief
- Check the version. Offline updates need at least 01.04.00.00 on the A1 and A1 mini, 01.07.00.00 on the P1 series and 01.08.02.00 on the X1; older firmware must update online first.
- Download the package. Get your model’s file from Bambu Lab’s firmware download page, linked from its offline firmware update guide. Do not rename or unzip it, or the update fails.
- Copy it over. On the A1 and P1 series, whose slots are not hot-swappable, eject the card from Settings > SD Card > Eject. On the H2, P2S and X2D, first format the USB drive on the printer under Settings > USB Storage > Format External Storage. Copy the package to the root of the card or drive.
- Start the update. Reinsert the card or drive, go to Settings > Firmware > Update Offline (Setting > General > Firmware Version > Update Offline on the X1) and pick the version.
- Wait. Leave the power on until the printer restarts by itself.
For a printer that never connects to the cloud, the LAN-only mode guide covers the offline update for each series.
Why is my Bambu printer not updating firmware?
A Bambu Lab printer shows its update prompt only when it is on Wi-Fi and bound to a Bambu Lab account. In LAN-only mode there is no cloud to fetch from, so use the offline update. If the printer is online and the update still will not install:
- Firmware too old. Bambu Lab’s P1 page says jumping from a very old version to the latest “may cause errors, such as (1.0.0 to 1.6.1)” and tells you to contact after-sales. Its A series page says some versions do not support a cross-version upgrade. To step through an intermediate version, Bambu Handy installs a chosen one under Device > ☰ > Settings > Firmware Version > “I want to update to a historical version”.
- Accessory mismatch. HMS_0500-0300-0002-000E, and codes such as 0500-0400-0001-0044 for AMS A, mean an accessory’s firmware does not match the printer’s. Keep the accessory connected and update from the printer, Bambu Handy or the offline package.
- AMS Hub added after the update. If the printer updated before the AMS Hub was connected, Bambu Lab says the hub then needs the offline update.
- AMS 2 Pro or AMS HT on older P1 or X1 firmware. A microSD update with either attached takes two passes on a P1 below 01.08.00.00 or an X1 below 01.09.00.00: disconnect them, update, reconnect, update again. On the X1 the first pass goes to 01.08.50.32.
Whether to install a given update at all is covered in the Bambu firmware controversy.
Bambu A1 or A1 mini firmware update stuck or not updating
Bambu Lab’s A series troubleshooting page covers both printers and adds one cause the P1 and X1 pages lack: a replacement TH board whose hardware version does not match the firmware. If you swapped the TH board before the update failed, Bambu Lab asks for a technical ticket with the printer log.
Neither printer can update offline below firmware 01.04.00.00. On older firmware, a repeated online failure means trying an intermediate version or opening a ticket. Bambu Lab’s A1 mini release notes for 01.08.01.00 (June 3, 2026) list a known issue: an offline update from 01.04.00.00 or earlier to 01.08.01.00 can leave garbled text on the screen. Run the offline update again or connect the printer to the network to fix it.
Bambu X2D firmware update stuck
Bambu Lab has no X2D-specific upgrade failure page as of October 21, 2026, so the steps above apply, with two documented differences:
- The offline update uses a USB drive, not a microSD card. Drives under 2 TB can be formatted to FAT32 on the printer; a larger drive must be formatted to exFAT on a computer first.
- The live view camera has its own firmware. HMS codes 0500-0100-0002-0012, -0013 and -0014 read “The live view camera firmware update encountered an error.” Restart and update again with the power kept on. If it still fails, power off, open the AP board cover, reseat the live view camera cable and retry. Then open a ticket with logs (step 8).
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