Problems with experiment

When I try to run experiment,it works up to a certain point and then blocks and goes out with this sentence

“WARNING Monitor specification not found. Creating a temporary one…
################ Experiment ended with exit code 1 [pid:17256] #################
658.6904 EXP Imported loopTemplate1.xlsx as conditions, 15 conditions, 1 params
658.6941 INFO Loaded monitor calibration from [‘2022_03_18 15:03’]”

My experiment consists in proposing a series of images in pairs and the respondent must choose the preferred one. The problem is that not all pairs of images are shown, but suddenly the program crashes and the error message I mentioned above appears