Hi Dietmar,
Nothing changed here. You are mistakenly attributing this error to 4.2. You must just never have made this mistake before.
Your decoy peptides do not have chromatograms. You may be able to solve this by re-importing your data files, if they are DIA or DDA, or even PRM if you collected data for your decoy precursors.
Hope this helps. Thanks for the helpful screenshot.
--Brendan