The evolving technological landscape in the digital era has a crucial influence on lifelong learning and the demand for problem-solving skills. In this paper, we identify associations between formal, non-formal and informal learning with sufficient problem-solving skills in technology-rich environments (TRE). We focus on adults' problem-solving skills in TRE as a novel approach to investigate formal, non-formal and informal learning based on data from the Programme for the International Assessment of Adult Competencies. This programme measured 16-64-year-old adults' proficiency in problem-solving skills in TRE. The total sample size was 61 654 individuals from 13 European countries. Our results clearly indicate that the skill levels of more than 50% of adults aged 16-64 years old seem to be insufficient to cope effectively in TRE. The findings suggest that the learning ecologies of adults are a combination of formal, non-formal and informal learning activities. The overall level of problem-solving skills in TRE was higher among individuals who indicated that they have participated either formal or non-formal learning activities, compared to those who have not. However, interestingly, the association between formal learning and problem-solving skills in TRE was not major. Instead, our results clearly indicate that informal learning seems to be highly associated with sufficient problem-solving skills in TRE. In practice, we outline those formal, non-formal and informal learning activities that adults perform when applying the skills in TRE. By recognising these activities undertaken by sufficient problem solvers, we can promote lifelong learning skills. Our findings can also be used as a starting point for future studies on lifelong learning.