Permision denied in non existent folder

Hi. The task show me this error. All the content is sync correctly, but shows this error. Doesn’t exist any folder like @eaDir or SYNO@. I don’t know what this mean. I’m not sure how to ignore this or solve it. Is annoying the red status in the task if all is fine.

This is the error. nas-ron error while traversing /volume1/backup/@eaDir/SYNO@.fileindexdb: permission denied

Review your sync log file to any error or warning message related to permission denied error.