Arguments are presented that the evidence for euv dayglow holes (Frank et al., 1986a) is best interpreted as an instrumentation artifact. The main arguments are that: (1) The holes are seen in several data streams derived from a single photmultiplier, a single ''Signal Conditioner'' circuit, and a single ''PM Tube Protection Circuit''. These common elements might be a source of cosmic ray-induced transients which interfere with the two data accumulation registers which they feed. (2) Most holes are single data words differing from normal data words by a single bit. (3) Holes seen at apogee are not distinct in signature from lower altitude observations, despite a requirement for a longer duration data event if the same physical event were obseved at lower altitude. (4) Most holes look the same in the scan direction as compared with a direction orthogonal to the scan, which is, on the average, impossible if the geophysical interpretation is valid.