What common mistake do developers make with Image handling, why does the mistake cause problems, and what is the safer approach?

What common mistake do developers make with Image handling, why does the mistake cause problems, and what is the safer approach? One recurring problem with image handling is applying it without understanding the boundary it protects. Trusting the original client filename or extension as proof that an uploaded file is safe. In addition, Image uploads should be validated and, when necessary, processed with a dedicated image library. Safer engineering approach: keep the responsibility in the correct layer, use the framework's supported API, validate and authorize inputs, avoid hidden side effects, and verify the behavior with tests.