uPVC door won't lock: common causes and fixes

Why a uPVC or composite door won't lock, from a dropped door to a failed gearbox, and what each costs to put right.

By LockedPrice · Updated 1 October 2026

The handle won't lift

On a uPVC or composite door you lift the handle to throw the bolts and hooks, then turn the key. If the handle won't go up, the hooks are usually catching on the keeps in the frame because the door has dropped or swollen.

Try lifting the handle while pushing the door firmly shut. If it then locks, the door needs adjusting.
Doors drop over time and move with the weather. Hinge and keep adjustments are usually a short job.

The handle lifts but nothing happens

If the handle feels loose or the bolts don't move, the gearbox in the multipoint mechanism has probably failed. A locksmith can often replace just the gearbox rather than the whole strip, if the make is still available.

The key won't turn

This points to the euro cylinder. It may be worn, or the handle isn't fully lifted. Never force the key; it can snap or break the cam inside. A worn cylinder is a quick swap, and a good time to fit an anti-snap one.

It won't lock in hot or cold weather

uPVC expands in heat and contracts in cold, so a door that's slightly out of line may only stick at certain times of year. Adjusting the hinges and keeps usually fixes it for good.

What not to do

Don't keep forcing the handle. That's how gearboxes break.
Don't leave a door you can't lock overnight without telling your insurer or getting it secured.

Questions

Why won't my uPVC door handle lift?

Usually the door has dropped or swollen so the locking hooks catch on the frame. Adjusting the hinges and keeps normally fixes it.

Can a uPVC door gearbox be replaced on its own?

Often, yes, if the make and size are still available. Otherwise the whole multipoint strip is replaced.

Is a uPVC door that won't lock an emergency?

If you can't secure your home overnight, yes. Otherwise book a planned repair.