Unlike linguistic fossilization, pragmatic fossilization has received scant attention in fossilization research. To bridge this gap, the present study adopted a typical-error method of fossilization research to identify the most frequent errors in pragmatic routines committed by Persian-speaking learners of L2 English and explore the sources of fossilization. In the first phase of the study, a pragmatic routines test was administered to 230 male and female participants to determine the typical errors and their persistence across different proficiency levels. In the second phase, retrospective interviews were conducted to explore the sources of the errors in pragmatic routines committed by 15 highly fossilized advanced learners. The findings revealed that the frequent errors in pragmatic routines were mainly due to sociopragmatic failure. It was found that first language transfer, lack of knowledge, and overgeneralizations were among the most frequent sources of pragmatic fossilization. This can be due to the nonauthentic poor-input pedagogical setting in which EFL learners fail to acquire the appropriate pragmatic routines. This study has implications for pragmatic instruction and pragmatic fossilization studies.