Beginner Flask Mistakes in 30 Seconds

You Forgot to Use @app.route()

[{"selector":"#anim-47e7c1f1-571a-4232-9924-0f854caeb8fe","keyframes":[{"offset":0,"transform":"rotate(-90deg) translate3d(0, -507.25291%, 0) rotate(90deg)","easing":"cubic-bezier(.5, 0, 1, 1)"},{"offset":0.29,"transform":"rotate(-90deg) translate3d(0, 0%, 0) rotate(90deg)","easing":"cubic-bezier(0, 0, .5, 1)"},{"offset":0.45,"transform":"rotate(-90deg) translate3d(0, -142.639518292%, 0) rotate(90deg)","easing":"cubic-bezier(.5, 0, 1, 1)"},{"offset":0.61,"transform":"rotate(-90deg) translate3d(0, 0%, 0) rotate(90deg)","easing":"cubic-bezier(0, 0, .5, 1)"},{"offset":0.71,"transform":"rotate(-90deg) translate3d(0, -48.493378196%, 0) rotate(90deg)","easing":"cubic-bezier(.5, 0, 1, 1)"},{"offset":0.8,"transform":"rotate(-90deg) translate3d(0, 0%, 0) rotate(90deg)","easing":"cubic-bezier(0, 0, .5, 1)"},{"offset":0.85,"transform":"rotate(-90deg) translate3d(0, -18.210379469%, 0) rotate(90deg)","easing":"cubic-bezier(.5, 0, 1, 1)"},{"offset":0.92,"transform":"rotate(-90deg) translate3d(0, 0%, 0) rotate(90deg)","easing":"cubic-bezier(0, 0, .5, 1)"},{"offset":0.96,"transform":"rotate(-90deg) translate3d(0, -7.913145395999999%, 0) rotate(90deg)","easing":"cubic-bezier(.5, 0, 1, 1)"},{"offset":1,"transform":"rotate(-90deg) translate3d(0, 0%, 0) rotate(90deg)","easing":"cubic-bezier(0, 0, .5, 1)"}],"delay":0,"duration":600,"fill":"both"}] [{"selector":"#anim-a9c9c3ce-817b-45ee-89a0-b319b98ccbfe","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-6d6e29ed-5db3-40f5-b70b-a90ab776cd35","keyframes":{"transform":["translate3d(0px, -165.96597%, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] Arrow

You’re missing live reload & error messages!

[{"selector":"#anim-3d4f51e5-347e-4506-84fa-1decb36e1d01","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-83c85670-3bd3-412b-9482-0bd7be997f57","keyframes":{"transform":["translate3d(100%, 0px, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-575ce0b5-dfa0-4de0-9f63-e463bcaac40f","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-ebb6baf5-ac77-4c5d-800e-14132b26980b","keyframes":{"transform":["translate3d(0px, -165.77267%, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-39d182cb-f4ac-466b-9f35-6bf3afc51c21","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-8084f12a-2c21-4ffd-86bd-a593acea7c5e","keyframes":{"transform":["translate3d(0px, 168.07149%, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}]

Hardcoding HTML? You’re Skipping Jinja2!

[{"selector":"#anim-1e94b589-98d8-43bb-a485-98968527b6a9","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-183edbe4-0d61-4a23-88fb-e8d0df68f765","keyframes":{"transform":["translate3d(-100%, 0px, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-cfa910e4-7a1b-4c5c-af1c-82524f9f7e36","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-b5a46515-784a-46a4-9b5d-8299cc91d610","keyframes":{"transform":["translate3d(0px, -162.88156%, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-deaf5e8f-9e93-412f-b4d9-34a28d0e1324","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-a7d65a83-f54c-49c8-8833-a5a51580f9e5","keyframes":{"transform":["translate3d(0px, 171.00269%, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}]

Not Using request.method? Welcome to 405 Errors.

[{"selector":"#anim-59b25b0d-a71e-4e00-8a6a-72651ea1fdbe","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-c817e9b3-c814-4546-b7b6-c4fc07664cbd","keyframes":{"transform":["translate3d(0px, -199.68125%, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-64a44a6c-b06d-4102-942e-5f2b5269b0ee","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-c9066522-e3c4-4757-98ec-b690a031c7e6","keyframes":{"transform":["translate3d(0px, -175.29243%, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-975bdf77-8b9f-4467-b411-827db10f3ed7","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-a3d1810f-91bf-4135-8852-31d90bdd924d","keyframes":{"transform":["translate3d(0px, 183.1746%, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}]

Bonus: Use Flask Extensions Early!

[{"selector":"#anim-0a237b6e-ce72-4acf-993d-82fbd02fe984","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-df397dcb-d9df-4888-b78d-c867a8d593c2","keyframes":{"transform":["translate3d(0px, 144.0466%, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-9d452bf6-bbbd-44f7-a077-82739f43b34c","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-c1a584a0-1908-4163-ab15-62316bdc1ff4","keyframes":{"transform":["translate3d(0px, -174.31456%, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-b842e076-a24d-4654-a08f-72647cf2275d","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}] [{"selector":"#anim-39dfb011-b9a8-4b7b-bf5b-98b8199437d5","keyframes":{"transform":["translate3d(0px, 154.41327%, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.2, 0.6, 0.0, 1)","fill":"both"}]

👉 Want Full Flask Tutorials?

[{"selector":"#anim-1fe1e53e-1be5-48d0-ac9f-b808fa3c1734","keyframes":{"transform":["scale(1)","scale(1.5)","scale(0.95)","scale(1)"],"offset":[0,0.33,0.66,1]},"delay":0,"duration":1450,"easing":"ease-in-out","fill":"both","iterations":1}] [{"selector":"#anim-e6f02057-302d-4ffe-832e-bdbb31c7d5e3","keyframes":[{"offset":0,"transform":"translate3d(0, -267.09402%, 0)","easing":"cubic-bezier(.5, 0, 1, 1)"},{"offset":0.29,"transform":"translate3d(0, 0%, 0)","easing":"cubic-bezier(0, 0, .5, 1)"},{"offset":0.45,"transform":"translate3d(0, -75.106838424%, 0)","easing":"cubic-bezier(.5, 0, 1, 1)"},{"offset":0.61,"transform":"translate3d(0, 0%, 0)","easing":"cubic-bezier(0, 0, .5, 1)"},{"offset":0.71,"transform":"translate3d(0, -25.534188312%, 0)","easing":"cubic-bezier(.5, 0, 1, 1)"},{"offset":0.8,"transform":"translate3d(0, 0%, 0)","easing":"cubic-bezier(0, 0, .5, 1)"},{"offset":0.85,"transform":"translate3d(0, -9.588675318%, 0)","easing":"cubic-bezier(.5, 0, 1, 1)"},{"offset":0.92,"transform":"translate3d(0, 0%, 0)","easing":"cubic-bezier(0, 0, .5, 1)"},{"offset":0.96,"transform":"translate3d(0, -4.166666712%, 0)","easing":"cubic-bezier(.5, 0, 1, 1)"},{"offset":1,"transform":"translate3d(0, 0%, 0)","easing":"cubic-bezier(0, 0, .5, 1)"}],"delay":0,"duration":600,"fill":"both"}] [{"selector":"#anim-d5c4d9b2-6c00-442a-8845-248dc67f3709","keyframes":{"transform":["translate3d(115.18987%, 0px, 0)","translate3d(0px, 0px, 0)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.4, 0.4, 0.0, 1)","fill":"both"}] [{"selector":"#anim-cec392d4-44f2-4713-aee1-32387d37a7bc","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.4, 0.4, 0.0, 1)","fill":"both"}] [{"selector":"#anim-bd100279-b579-42b6-89d3-ccdc7591efba","keyframes":{"transform":["scale(0.15)","scale(1)"]},"delay":0,"duration":600,"easing":"cubic-bezier(0.4, 0.4, 0.0, 1)","fill":"forwards"}]

🎨 Turn Your Ideas into Stunning AI Images

[{"selector":"#anim-bdf249a5-cd5d-43ed-bdef-b27b17020104","keyframes":{"opacity":[0,1]},"delay":0,"duration":600,"easing":"cubic-bezier(0.4, 0.4, 0.0, 1)","fill":"both"}] [{"selector":"#anim-e0d8da10-5c21-4997-a2e6-2e95c94c9daa","keyframes":[{"offset":0,"transform":"translate3d(0, -509.85337%, 0)","easing":"cubic-bezier(.5, 0, 1, 1)"},{"offset":0.29,"transform":"translate3d(0, 0%, 0)","easing":"cubic-bezier(0, 0, .5, 1)"},{"offset":0.45,"transform":"translate3d(0, -143.370767644%, 0)","easing":"cubic-bezier(.5, 0, 1, 1)"},{"offset":0.61,"transform":"translate3d(0, 0%, 0)","easing":"cubic-bezier(0, 0, .5, 1)"},{"offset":0.71,"transform":"translate3d(0, -48.741982172%, 0)","easing":"cubic-bezier(.5, 0, 1, 1)"},{"offset":0.8,"transform":"translate3d(0, 0%, 0)","easing":"cubic-bezier(0, 0, .5, 1)"},{"offset":0.85,"transform":"translate3d(0, -18.303735983%, 0)","easing":"cubic-bezier(.5, 0, 1, 1)"},{"offset":0.92,"transform":"translate3d(0, 0%, 0)","easing":"cubic-bezier(0, 0, .5, 1)"},{"offset":0.96,"transform":"translate3d(0, -7.953712572%, 0)","easing":"cubic-bezier(.5, 0, 1, 1)"},{"offset":1,"transform":"translate3d(0, 0%, 0)","easing":"cubic-bezier(0, 0, .5, 1)"}],"delay":0,"duration":600,"fill":"both"}]

Beginner Flask Mistakes in 30 Seconds

What Every Beginner Gets Wrong

You Forgot to Use @app.route()

You’re missing live reload & error messages!

Still Using debug=False While Testing?

Hardcoding HTML? You’re Skipping Jinja2!

Use templates for cleaner separation of code and UI.

Not Using request.method? Welcome to 405 Errors.

Always check request types for forms

Bonus: Use Flask Extensions Early!

Flask is powerful — but Flask + extensions = superpower.

👉 Want Full Flask Tutorials?

✅ Visit our beginner-to-pro Flask guide. 🎓 Learn by building real apps.

🎨 Turn Your Ideas into Stunning AI Images

👉 ChatDocsAI.com