Form 4: debris in the tank (errors 1.1.6, 1.1.7, 1.7.2, 1.7.3), damaged film or tank not detected
Guide based on the manufacturer's official documentation; usi3d has not yet verified it on a machine.
Technology: Resin · Brand: Formlabs · Symptoms: The printer shows an error code or message, The print sticks to the vat film (FEP), Resin leak or torn film in the vat · Updated on 9 October 2026
Symptom
After a failed print, the Form 4 or Form 4L reports that the mixer hit debris (1.1.6 or 1.7.2) or that the build platform found debris when lowering (1.1.7, 1.7.3 or 1.13.1); or it says the tank is missing (1.6.9), is not locked (1.6.12) or has exceeded its lifetime (1.6.11); or you see cured resin stuck to the film, or scratches, dents or small dots on the film that show up on parts.
Likely causes, from most to least likely
- Cured resin from a failed print, floating in the tank or stuck to the film (also under the wear strips along the film edge).
- Debris or damage on the build platform: cured resin, deep scratches or burrs.
- The mixer is not fully seated, is damaged or has debris, or the tank lip is dirty; with very viscous resins (Rigid 4000, Rigid 10K) a false warning can appear.
- The tank is not locked with its latches, the latches are damaged or the tank RFID board is disconnected.
- Damaged film: punctures or gouges (leak risk), scratches from cleaning with the wrong materials, or cavitation from always printing in the same area.
- The tank has reached the end of its lifetime.
Checks to tell which one it is
- Wearing gloves, go over the film with the plastic scraper looking for cured resin, including under the wear strips.
- Check the build platform: resin debris, deep scratches or burrs.
- Hold the film against the light: punctures or gouges mean the tank must be replaced; 1 mm snowflake-like dots mean cavitation.
- Check that the tank is locked with the latches and that the mixer is fully seated and moves freely.
Before you start
Uncured resin irritates skin and eyes: wear nitrile gloves and safety glasses, ventilate the room and do not look at the UV light. Before taking anything apart or cleaning it, switch the printer off and unplug it, unless a step says otherwise. If in any doubt, stop and ask a professional.
Step-by-step fix
Print a cleaning sheet
With the printer idle, insert the tank that failed and close the latches; remove the mixer, build platform and cartridge. Go to Maintenance → Print cleaning sheet, place the cleaning sheet holder at the centre of the right edge of the LPU (or a clean piece of support with a raft at a corner of the LPU) and press Start: it takes 2 to 15 seconds depending on the resin. When it finishes, peel the sheet off carefully and refit the wear strips if they came loose.
Check: The sheet comes out with the debris attached and the film is clean.
If that does not fix it: Remove what is left by hand (next step).
Remove debris by hand and filter
Wearing gloves, use only the plastic scraper, flat side, without force and without digging in the corners; never metal tools, which damage the film. Then strain the resin through a fine paint filter (190 micron).
Check: You cannot feel any cured resin on the film or in the resin.
If that does not fix it: Check the build platform and mixer (next step).
Build platform and mixer
Remove cured resin from the build platform with a scraper; if it has deep scratches or burrs, clean or replace it. Check that the mixer arm is fully seated in the mixer body and clean the tank lip it rides on. With viscous resins, mix the resin by hand and turn on Resin preheating in Settings → Configuration.
Check: The debris error does not come back.
If that does not fix it: Try another tank if you have one; if it continues, contact Formlabs support or your reseller.
Clean the film and wear strips
Remove the wear strips, clean them with isopropyl alcohol on a lint-free wipe and click them back in. To clean the film, empty the resin into an opaque container and wipe with isopropyl alcohol on a lint-free cloth (inside, or underneath with the tank upside down); never paper towels or abrasive cleaners. Keep resin from getting between the two film layers.
Check: The film is clean and streak-free.
If that does not fix it: If the film is damaged, consider replacing the tank (last step).
Tank not locked or not detected
For 1.6.12, press down on the sides of the tank with your thumbs and close the latches; if they are damaged, replace them. For 1.6.9, reinsert and secure the tank; if it continues, reboot, update the firmware and try another tank.
Check: The printer recognises the locked tank.
If that does not fix it: If it fails with every tank, the tank RFID board needs checking: contact support.
When to replace the tank
A punctured or gouged film means the tank must be discarded straight away: besides curing badly, it can leak resin into the printer. With dents or cavitation that show on parts, use Layout in PreForm to print in another area or replace the tank. With 1.6.11, the tank has exceeded its recommended lifetime: consider replacing it.
Check: Parts come out without marks from the film.
If that does not fix it: Contact Formlabs support if you are unsure about the tank's condition.
Prevention
- Inspect the tank between prints and before storing it.
- Spread parts across different areas of the tank to avoid cavitation.
- Never use metal tools or paper on the film: only the plastic scraper and lint-free cloths.
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
The Formlabs Form 4 family: Form 4 and Form 4L.
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.