In order to trace the transmission of COVID-19, digital contact tracing (DCT) provides an enormous value for the public health. However, the acceptance of the German contact tracing app, the Corona-Warn-App (CWA), falls short of the expected coverage in the general public. Accordingly, this study focuses on investigating the influencing factors on the CWA’s acceptance to demystify the missing puzzle and to face future pandemics. To assess this objective comprehensively, we investigate personality traits (guiding perception and behavior), subjective norm (expressing social influence), and trust in technology on acceptance variables. Our empirical results emphasize that besides the personality traits conscientiousness and agreeableness, perceived usefulness, subjective norm, and trust in technology play a vital role for engagement with the CWA. Our research offers starting points for the use of mobile health solutions, particularly in early epidemic stages.