Prusa error 13812 (Crash Recovery Home Fail) appears on the MK4 and its equivalents are #31812 on the CORE One, #26812 on the MK4S, #27812 on the MK3.9S, #21812 on the MK3.9, #28812 on the MK3.5S, #23812 on the MK3.5, #17812 on the XL, and #12812 on the MINI. After detecting a mid-print collision and pausing, the printer attempted to re-home the affected axis to determine its exact position for print recovery, but the homing sequence itself failed.

What the Error Means

When Prusa’s crash recovery feature detects a collision, it pauses the print, moves the affected axis to the home end-stop to re-establish position, and then attempts to resume from the last known coordinates. If homing fails during this recovery sequence — because the same obstruction that caused the original crash is still blocking the axis, because a belt lost tension during the crash impact, or because the crash damaged the end-stop or sensor — the firmware cannot safely calculate the resume position and raises this error. At this point, the current print is likely unrecoverable.

Step-by-Step Fix

1. Check for physical obstructions along the X and Y axes. Look for anything that might have fallen onto the print surface, a blob of filament dragging from the nozzle, or wiring that has come loose and is lying across an axis path.
2. Manually move each axis by hand. With the printer off, push the X carriage and the Y bed through their full travel. Both should move freely and smoothly. Any binding point will prevent homing.
3. Inspect belts for damage or slippage. A crash impact can sometimes jump a belt off its idler pulley or cause it to lose tension. Inspect both the X and Y belts visually and re-tension or re-route as needed.
4. Restart the printer and retry homing. After clearing any obstructions and verifying mechanical freedom, restart the printer and allow it to home from the startup sequence. A clean power-cycle home may succeed where the recovery home failed.
5. Accept that the current print may be lost. If homing cannot complete even after clearing obstructions, the position data for the current print cannot be recovered. Start a new print after resolving all mechanical issues.

Parts Required

• No replacement parts are typically required for this fix — basic tools only
• Replacement belt (if the belt was damaged during the crash impact)

If homing consistently fails even after clearing all obstructions and verifying belt integrity, contact Prusa Support at help.prusa3d.com for end-stop and motor diagnostic assistance.

Frequently asked questions

What does Prusa 13812 mean?

Prusa error 13812 (Crash Recovery Home Fail) appears on the MK4 and its equivalents are #31812 on the CORE One, #26812 on the MK4S, #27812 on the MK3.9S, #21812 on the MK3.9, #28812 on the MK3.5S, #23812 on the MK3.5, #17812 on the XL, and #12812 on the MINI. After detecting a mid-print collision and pausing, the printer attempted to re-home the affected axis to determine its exact position for print recovery, but the homing sequence itself failed.

How do I fix Prusa 13812?

Prusa error 13812 means the printer failed to home an axis after a crash was detected. Learn how to check for obstructions and belt issues to restore print recovery.