DIAGNOSIS The rug's fringe, tassels, or loose fibers are getting sucked up into the main brush chamber and wrapping around the brush's axle ends or the sensors, triggering the error falsely.
FIX 1) Flip the robot over and remove the main brush. 2) Look closely at the two silver axles the brush spins on. Use scissors or a seam ripper to cut away any tiny threads or hairs wound tightly around them—this is the usual culprit. 3) Also, check the two optical sensors (little clear windows) inside the brush chamber. Wipe them clean. Reassemble and test.
IF THAT DIDN'T WORK The rug might simply be too high-pile or shaggy for this model. In the Ecovacs app, you can create a 'No-Go Zone' over the entire rug area to keep the vacuum off it, or switch to mopping-only mode when cleaning that room.
HEADS UP This error can also be caused by a worn-out main brush where the paddles are bent and hitting the housing. If your brush is old, try a replacement—the new ones have stiffer paddles.