What is a common mistake that gets D4 student visa applications refused?

Consulates assess whether you genuinely intend and are able to study, and whether you can support yourself without working illegally or relying on the State. Weak or short-dated proof of funds, missing accommodation evidence, or an offer from a non-accredited programme are common reasons applications fail.

Avoid this by securing admission to a recognised institution, gathering clear and recent financial evidence covering your stay, and arranging accommodation and valid health insurance before you apply. Submitting a complete, consistent file the first time greatly reduces the risk of refusal or delay.