Why your printer might not read a file, or freeze mid-print, and how to fix it
An issue with the USB key
The probable cause is usually a corrupted USB stick (or SD/microSD card). Most low-cost 3D printers (sub-$1000) come with very cheap USB sticks, and these often electronically fail or corrupt data, this applies to FDM printers too. A print job can run for hours with constant read access to the card, and low-quality sticks tend to fail quickly under that load.
This can also show up mid-print: your printer may appear to pause on its own, with the touchscreen or buttons unresponsive, the printer has frozen and the only fix is to restart it. This can affect printers from any brand and has the same root cause as a file not being recognized.
Recommended fix: use a good-quality, brand-name USB stick (16–32 GB) formatted as FAT32. Some printers also support exFAT.
File sliced for the wrong printer or format
With so many printers supported in Lychee Slicer, it's easy to select the wrong one from the list, especially with printers that share similar names or have multiple format variants across manufacturer revisions.
Double-check you've selected the correct printer and format. If the format you need isn't listed, deleting and re-adding the printer will refresh its available settings.
Other possible causes
- A hardware issue — if no USB key is recognized and no other files can be detected, this may point to a problem with the printer itself.
- An unexpected firmware update — printer manufacturers sometimes push firmware changes that affect Lychee Slicer compatibility without notifying us.
If none of the above resolves it, or you're dealing with a slice file issue, contact our support team.