Most house’s these days have UPVC doors like the one in the picture (Image below) . MP Handyman Services has done maintenance and replacements to hundreds of these every year. If you door handle is difficult to lift or isn’t running as smoothly as normal. Maybe when you turn the key it feels stiff and difficult to turn or the door needs leaning against to get it to lock. These are all signs that some servicing, adjustment or even replacements may be required. The same goes for traditional wooden doors; if the lock or handle feel tight or are making unfamiliar noises then these to are signs of possible problems.
Also try a small squirt of WD40 in the lock or any other moving parts on an annual basis; this will help the lock function correctly. Getting a door open that has a jammed lock in the closed position can be expensive; not to mention the inconvenience of being locked out of your home.