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Background: Inherited chronic mucocutaneous candidiasis (CMC) is often caused by inborn errors of immunity, impairing the response to, or the production of IL‐17A and IL‐17F. About half of the cases carry STAT1 gain‐of‐function (GOF) mutations. Only few patients have been reported with mutations of TRAF3IP2, a gene encoding the adaptor ACT1 essential for IL‐17 receptor(R) signaling. We investigated a 10‐year‐old girl with CMC, carrying a heterozygous variant of STAT1 and compound heterozygous variants of TRAF3IP2. Methods: By flow cytometry, STAT1 levels and phosphorylation (CD14+) as well as IL‐17A, IL‐22, IFN‐γ, and IL‐4 production (memory CD4+ T cells) were determined. ACT1 expression and binding to IL‐17RA were assessed by Western blot and co‐immunoprecipitation in HEK‐293T cells transfected with plasmids encoding wild‐type or mutant HA‐tagged ACT1 and Flag‐IL‐17RA. We evaluated IL‐17A responses by measuring luciferase induction under a NF‐κB‐driven reporter system in HEK‐293T cells and Gro‐α secretion in fibroblasts. Results: A STAT1 variant (c.1363G>A/p.V455I) was identified by next‐generation sequencing and classified as likely non‐pathogenic as functional testing revealed normal STAT1 expression and phosphorylation upon IFN‐γ. We also found compound heterozygous variants (c.1325A>G/p.D451G and c.1335delA/p.K454fs11*) of TRAF3IP2. By overexpression, despite normal protein expression, and impaired (K454fs11*) or normal (D451G) interaction with IL‐17RA, both mutant alleles resulted in impaired NF‐κB activation. Patient's fibroblasts displayed abolished GRO‐α secretion upon IL‐17A stimulation. Finally, ex vivo CD4+ T cells showed increased IL‐17A, IL‐22, and IL‐4 and normal low IFN‐γ expression upon stimulation. Conclusion: We identify novel compound heterozygous variants of TRAFP3IP2 causing autosomal recessive ACT1 deficiency in a child with CMC and provide a review of the current literature. [ABSTRACT FROM AUTHOR]