A series of practical articles aims to introduce the reality of trial and error behavior in diverse R&D activities. There are one article and two interview articles; (i) trial and error on management of manufacturing technology in Toshiba, (ii) trial and error management in automotive parts maker in Hitachi automotive systems, and (iii) collaborative trial and error for B2B product innovation in Okitsumo Inc. Those practice will contribute to promoting understandings of how companies manage uncertainty by encouraging trial and error behaviors as well as relevant challenges.