This study focuses on language use errors in writing simple essays about family assigned to primary school students. The research sample included third grade students of Sidamukti II State Primary School in Majalengka District, Majalengka Regency, West Java Province. Sidamukti II State Primary School was selected because the school is located in a subdistrict that borders a subdistrict in Sumedang Regency. This may affect the students' mother tongue Sundanese, which is Majalengka dialect Sundanese and different from Priangan dialect Sundanese spoken in Sumedang Regency. Thus, this situation affects the students' proficiency in Indonesian as a second language. The results of the analysis are presented in the form of narratives and tables, while the error analysis is based on Tarigan's theory of language errors. Based on the analysis process, it was found that errors in the written language of Class III students in the form of lexical errors appeared in the texts of 17 students, phonological errors committed by 18 students, morphological errors were found in the essays of 23 students, and syntactic errors were found in the narratives written by 25 students. When converted into percentage form, it can be concluded that lexical errors amounted to 68%, phonological errors amounted to 72%, morphological errors covered 92%, and syntactic errors reached 100% or covered the entire research instrument studied. In addition, there were two invalid essays due to the similarity of structure, diction and use of punctuation, which reached 100%. Some of the errors made by the students are influenced by their mother tongue and ignorance of the standard language varieties in Indonesian as the target language in this observation.