The blind leading the blind
Definition 1 of 1
Pro Tip 1/3Metaphorical Meaning
Understand it's a metaphor for lack of guidance or knowledge. 
With all new interns managing the project, it's the blind leading the blind.
Pro Tip 2/3Critical Tone
It often implies a criticism or frustration about the situation. 
Asking toddlers to organize their playroom is like the blind leading the blind.
Pro Tip 3/3Not Literal
Don’t take it literally; it doesn't refer to visual impairment. 
This manual is useless; it's the blind leading the blind.