path: psychtoolbox-3_3.0.19.14.dfsg1-1/Psychtoolbox/PsychHardware/PsychVRToolbox/PsychOpenXR.m % Does the metrics fifo file exist at the expected location? And monado-service is running? monadometricsfile = getenv('XRT_METRICS_FILE'); [rc, ~] = system('pidof monado-service'); if exist(monadometricsfile, 'file') && (rc == 0) % Yes. Try to open it. monado-service must have been launched with proper