diff --git a/admin/api/sync.go b/admin/api/sync.go
index baaa5125..22f63154 100644
--- a/admin/api/sync.go
+++ b/admin/api/sync.go
@@ -15,6 +15,13 @@ import (
 	"github.com/gin-gonic/gin"
 )
 
+func flatifySyncErrors(errs []error) (ret []string) {
+	for _, err := range errs {
+		ret = append(ret, err.Error())
+	}
+	return
+}
+
 func declareSyncRoutes(router *gin.RouterGroup) {
 	apiSyncRoutes := router.Group("/sync")
 
@@ -71,7 +78,7 @@ func declareSyncRoutes(router *gin.RouterGroup) {
 
 	apiSyncRoutes.POST("/themes", func(c *gin.Context) {
 		_, errs := sync.SyncThemes(sync.GlobalImporter)
-		c.JSON(http.StatusOK, errs)
+		c.JSON(http.StatusOK, flatifySyncErrors(errs))
 	})
 
 	apiSyncThemesRoutes := apiSyncRoutes.Group("/themes/:thid")
@@ -135,7 +142,7 @@ func declareSyncExercicesRoutes(router *gin.RouterGroup) {
 		theme := c.MustGet("theme").(*fic.Theme)
 		exceptions := sync.LoadException(sync.GlobalImporter, theme)
 
-		c.JSON(http.StatusOK, sync.SyncExercices(sync.GlobalImporter, theme, exceptions))
+		c.JSON(http.StatusOK, flatifySyncErrors(sync.SyncExercices(sync.GlobalImporter, theme, exceptions)))
 	})
 	apiSyncExercicesRoutes := router.Group("/exercices/:eid")
 	apiSyncExercicesRoutes.Use(ExerciceHandler)
@@ -147,7 +154,7 @@ func declareSyncExercicesRoutes(router *gin.RouterGroup) {
 		exercice := c.MustGet("exercice").(*fic.Exercice)
 
 		_, _, errs := sync.SyncExercice(sync.GlobalImporter, theme, exercice.Path, nil, exceptions)
-		c.JSON(http.StatusOK, errs)
+		c.JSON(http.StatusOK, flatifySyncErrors(errs))
 	})
 	apiSyncExercicesRoutes.POST("/files", func(c *gin.Context) {
 		exercice := c.MustGet("exercice").(*fic.Exercice)
@@ -179,7 +186,7 @@ func declareSyncExercicesRoutes(router *gin.RouterGroup) {
 		exceptions := sync.LoadException(sync.GlobalImporter, theme)
 
 		_, errs := sync.SyncExerciceHints(sync.GlobalImporter, exercice, sync.ExerciceFlagsMap(sync.GlobalImporter, exercice), exceptions)
-		c.JSON(http.StatusOK, errs)
+		c.JSON(http.StatusOK, flatifySyncErrors(errs))
 	})
 	apiSyncExercicesRoutes.POST("/flags", func(c *gin.Context) {
 		exercice := c.MustGet("exercice").(*fic.Exercice)
@@ -188,7 +195,7 @@ func declareSyncExercicesRoutes(router *gin.RouterGroup) {
 		exceptions := sync.LoadException(sync.GlobalImporter, theme)
 		_, errs := sync.SyncExerciceFlags(sync.GlobalImporter, exercice, exceptions)
 		_, herrs := sync.SyncExerciceHints(sync.GlobalImporter, exercice, sync.ExerciceFlagsMap(sync.GlobalImporter, exercice), exceptions)
-		c.JSON(http.StatusOK, append(errs, herrs...))
+		c.JSON(http.StatusOK, flatifySyncErrors(append(errs, herrs...)))
 	})
 }