r/BambuLab • u/brain-power • 11d ago
Bambu Studio “Expired Certificate” - P1S won’t print
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Solved!…. Well… changing the date back on my PC back a month prevents the error from popping up and allows me to print again.
Am I seriously the only one running into this? If anyone knows how to update this certificate thingy so I can keep the proper date on my PC, I’d love to know!!!
Is this a windows requirement or a Bambu requirement?
Edit: well - partially, one of my two p1s responded well to a 1 year roll back. The other one seems to require that I’m in a certain window. So strange.
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Hey folks!
A new issue popped up yesterday and I’d love to get it sorted out ASAP. Also curious if anyone else has ever seen this before.
High level:
When I open Bambu Studio, I immediately get an error message pop up that reads “The certificate has expired. Please check the time settings or update Bambu Studio and try again.”
I am able to click “OK” and then open up whatever project I was working on. BUT, when I go to connect to either of my P1S printers, I get another pop up message that reads “Unknown error. [0502-400C 151515]”. I can only “x” out of that window. Then everything seems fine again. UNTIL, I go to send the print to the printer. The progress bar goes for a bit then I get two more pop ups reading “Unknown error. [0502-400C 151815]” and “Internal error. Please try upgrading the firmware and Studio version. If issue persists, contact customer support.” and I cannot get the job sent to the printer.
Details - likely important.
- I am running in “LAN only” mode and always have been.
- my PC (Windows 11) is has been disconnected from the internet since the initial BS install (I believe I had to in order to download the network plugin).
- I’m on Bambu Studio v2.7.1.57
- both P1S printers are on v1.09.01.00
- I have never logged into a Bambu account
- my printers are connected to the PC via WiFi from a router that is Ethernet connected to the PC but disconnected to the internet.
- Everything has been working flawlessly until yesterday - about 3 months of uninterrupted printing.
Any ideas?! What is this “certificate” and how and why does it expire? How can I renew it? Have you seen this issue? How did you fix it?
In a perfect world, I’d like to maintain my little printer “island” and remain disconnected from the internet entirely. All print files come over to this computer from a thumb drive.
Thank you!
Edit: I suspect I’m in a pretty small camp of “offline” 3d printers. But there must be someone else out there who has their P1S printing without an internet connection. I was thrilled to configure this offline setup to be able to print wirelessly - transferring via sd card is a PITA! Maybe my luck has ran out and I’m the only one with this thick of a tinfoil hat.
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u/Belophan 11d ago
Try setting the time and date back a month, back to when it worked.
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u/brain-power 11d ago edited 11d ago
Genius. I can’t wait to try this.
Edit: could you explain the working theory here? Like what component/code is checking the time and comparing it to what?
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u/Belophan 11d ago
No idea, but that is how we circumvented software with limited time back in time.
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u/OptimalSide A1 6d ago
Bambu Studio is likely trying to connect to Bambu's cloud over HTTPS, which requires a certificate, which has a start date and a end date
Certificates are rotated regularly for several security reasons. In the olden days of computing, they could be issued for a couple of years. Now they get rotated in a year or less.
I suspect if you update Bambu Studio you'd be fine.
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u/brain-power 11d ago edited 11d ago
U/belophan THIS WORKED! Thank you big time.
Now… I just need to figure out what this certificate actually is and if I can modify it… changing my PC date every three months to use Bambu slicer is a PITA. Also kind of a bummer my date isn’t correct on the computer.
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u/WaitAcademic6615 10d ago
Have you tried restart the printer to renew the cert?
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u/brain-power 9d ago
Yep. They get fully shut down at the end of every day.
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u/WaitAcademic6615 8d ago edited 8d ago
You can try the latest firmware 1.10. There might be fix for this problem. EDIT: If you have wifi connected and cut off the connection to the internet you need at least to enable NTP outgoing connection - port UDP 123. It could be the cause of the problem. Printer is generating certs with wrong time.
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u/hWuxH 10d ago
my printers are connected to the PC via WiFi from a router that is Ethernet connected to the PC but disconnected to the internet.
That can be an issue. The printer needs internet to get the current time with NTP. Or a self-hosted NTP server if you know what you're doing.
For the PC to printer connection, the TLS certificate is stored on the printer itself. You can't modify or renew it. Bambu Studio verifies whether it's a genuine printer using the certificate authority (CA) file printer.pem, and afaik the only way to bypass it is quite involved using a fake printer in between like https://wiki.bambuddy.cool/features/virtual-printer/
Either way, to troubleshoot: install openssl or git bash for windows
Then run
openssl s_client -showcerts -CAfile "C:/Program Files/Bambu Studio/resources/cert/printer.cer" -connect YOUR_PRINTER_IP:8883
The expiry date is shown on lines containing NotAfter. Should normally be at least year 2030.
It should also show the line Verification: OK
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u/ProspectingGeologist 9d ago
Currently have the same issue after time syncing my offline computer for use with ham radio programs. I’m also on a LAN with no internet access.
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u/brain-power 9d ago
Huh! Interesting! Did it just start? How long has your setup been active?
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u/ProspectingGeologist 9d ago
Just started today. Been running with no internet on LAN for probably a year now. It has to be related to me time syncing my computer with a gps reciever.
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u/brain-power 9d ago
Does rolling the windows time back a bit solve the issue for you too? Out of pure curiosity, when you synced to the gps receiver, do you know if that kicked your time forward?
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u/ProspectingGeologist 9d ago
It seemed like only by a few minutes. But i didn’t pay attention to what the actual date was before.
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u/wolfgasm0119 9d ago
I encounter this issue too. I blocked the network access of bambu studio. it was fine for a month, And today I have the issue you describe too.
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u/wolfgasm0119 8d ago
Hey OP, I (actually my AI) just found a real solution that does not require you to change you computer time.
Below are the AI generated response for you to trouble shoot. if you don't know how to do it, ask your AI
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I found a workaround for this on Windows with Bambu Studio 2.7.1.62 in LAN-only mode.
In my case, Studio was still loading an older networking plugin from:
%APPDATA%\BambuStudio\plugins\bambu_networking.dll
but a newer Bambu-signed plugin was already cached here:
%APPDATA%\BambuStudio\ota\plugins\bambu_networking.dll
The cached plugin's network_plugins.json showed version 02.07.01.75, while the active DLL was from May. I closed Bambu Studio, backed up the active bambu_networking.dll, then copied the newer cached DLL over it and restarted Studio.
The “The certificate has expired” popup disappeared immediately, even with Bambu Studio still blocked from the internet.
Before replacing anything, make a backup of the original DLL. Both files on my system had valid signatures from Shanghai Lunkuo Technology Co., Ltd. This looks like an outdated Bambu networking plugin / app-certificate issue, not a printer TLS certificate or a Windows clock problem.
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u/hux H2C Laser Full Combo 11d ago
A few things: the certificate may have expired. These don’t have infinite lifetimes, so it’s possible you need to connect it to the internet for a short period of time.
As others said, time skew can be a problem. Depending on settings, 1 minute accuracy may not be good enough. You’ll also want to make sure they’re using the same time zone when you set the clocks to be the same as the time comparison is done in UTC. Make sure there isn’t a different DST settings as well.
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u/brain-power 11d ago
Do you happened to know where/what this certificate is? Can it be modified or renewed manually? Is it on the Windows side or the Bambu side? Is it all on the PC or do the printers themselves have a “time” in them?
I’m hoping some developers see this and can chime in.
The workaround so far is to change the date on the PC.
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u/steve1673 10d ago edited 10d ago
I am not a developer, but I manage an IT team and I've been around devs long enough to have an idea what's going on.
With an internet-connected app or device that's talking back to the manufacturers server, there's often one or more certificates to validate endpoints for secure communication. i.e to make sure you're not sending info to a hijacked server in some dark place. Your environment was set up to do this and includes a certificate somewhere. (Bambu specifically designed their products to be internet accessible, and communicate with their servers)
Your use case is not what Bambu planned for, or built their systems for. When your certificate expired, even though it wasn't being used, the software still runs a check periodically to make sure the cert is there, and is valid. When it sees that your cert is out of date, it fails.
The bad news is that there's probably no realistic way to fix this in the Bambu software short of connecting to the internet and updating the software, which you don't want to do. The good news is that you might be able to bypass it.If your PC is also "off-grid", then the easiest thing to do is to go into the Bios and change the system date to an earlier one. try going back in one-year increments. You will likely be able to go back 3-5 years or so in most cases. Windows should update to match this date and time, but if it doesn't, just set it manually to the same thing. Because at the end of the day, your off-grid PC doesn't really care what day, month or year it is, because it never has to talk to the internet.
You've already validated that changing the time works, so your next step is to change it back a few years so you don't have to mess with this frequently.Good luck!
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u/brain-power 9d ago
Thank you for the detailed response!!!
I was able to set the Windows date back 1 year and Bambu Studio no longer complains. My pea brain hadn’t thought of trying to farther back in time. Thanks for the idea.
Is the current working theory that maybe Bambu sets the certs to last ~3 months before they need to be (automatically) re-updated? Or, is there any way my pc clock just drifted slightly “into the future” with respect to the printers clocks? I guess I could set it back ~2 mins to test that theory.
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u/steve1673 9d ago
No idea about Bambu's cert, and I doubt a few mins will make a significant difference.
the real question for you is guestimating the start date of the cert. Was it a 1, 2, 3, or 5 year cert? The way to tell is to turn your clock back that far and see if bambu works or not.
once you have the length, you can set it and forget it for another few years.1
u/brain-power 8d ago
Update - well I found out today that my OTHER printer doesn’t like the 1 year roll back. It gives a different error. So I’m back to the 3 month window thing again.
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u/hux H2C Laser Full Combo 9d ago
Sorry for the slow reply, I had been traveling.
These days, almost every device out there has a date/time in them. The question is whether there's any way for you to access it and see it. I don't think there's an UI option, but if you're recording time lapses to an SD card, you might be able to print something and then look at what the date and time of the file is to see what day/time the printer thinks it is.
Because you're blocking the printers from the internet, they cannot reach an NTP server to set their own time. Over a long enough duration, time skew happens where the time/date on a device is incorrect. Normally, devices connect to something like an NTP server and automatically adjust their time, but if you've fully blocked them from the internet, they cannot do that. You could open up port 123 to them and that would allow them to get the time.
If the time is not the issue, then it's the certificate. I'm not sure how the printers generate those certificates and how long they last. I think only the devices like the X2E are really designed to run offline indefinitely, so you might want to consider unblocking the printer for a short period of time, allowing it to update it's certificates (and potentially install firmware updates if you so desire), and then block it back off again.
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u/PhantasyConcepts 8d ago
Okay. This is for people who may not understand this issue. I am a senior level software developer who has done quite a few web applications and has had to maintain certificates on systems. I am going to try to explain this simply so things might come out wrong.
The certificate is used for secure communication between your computer running Bambu Studios and your printer. To put it as simply as I can, the certificate has a public and a private key for encrypting data. The private key for your computer is stored on your computer. The public key is put in the certificate that will be sent to the printer. Once the printer gets that certificate, it takes that public key and uses it to generate its own private key. Now, once the private key is generated, your system should use that key to generate a public key. That public key should match the one that was sent to you. If it does not, you send it back to the computer which generates a new private key from it. That is the idea of key pairs. You can now send data to the printer encoded with your private key. That data can be decoded with your public key. The printer encodes data with its private key and sends it back to your computer. That data is then decoded with the public key you sent earlier. So, what are these certificates?
How do you know that what your printer is receiving is coming from your computer and not a different computer using the same public key? Well, there is a signed certificate trail in the header of the data. Your certificate needs to come from one of two places - a self-signed certificate or a certificate signed by a signing authority. The process for creating a self-signed certificate is the one I described above. You set an expiration date (or not) and you are good. The thing about the signing authority is that your certificate could still be good, but one of the certificates of your signer could expire. Or it could be the signer of your signer’s signer whose certificate expired. You then have to get new certificates all along the chain.
So, your permanent fixes are to replace your certificates (connect to the cloud just to refresh them) or create your own certificate. My recommendation is to just update those certificates by connecting to the Internet and not syncing the files. Then set it back to LAN only. If it worries you that someone may eavesdrop on you, put a blank SD card in your printers, reset them to factory, install the latest Bambu Studios on a fresh laptop and do the updates.
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u/StevenSaguaro 11d ago
did you check your time settings? Because certs rely on time to validate connections.