DIAGNOSIS This is the classic "suction motor overload" protection kicking in, almost always because the filters are clogged. The vacuum thinks it's struggling to breathe and shuts down to avoid burning out.
FIX Power it off, unplug it, and check the main airpath. Start with the pre-motor filter (the big foam one in the top of the canister). Take it out and tap it clean over a trash can, or wash it with cold water if it's really dirty—just let it dry COMPLETELY for 24 hours before putting it back. While you're at it, check the exhaust filter (the HEPA one at the back) and the bag. If the bag is over 3/4 full, replace it. A full bag is a huge restriction.
IF THAT DIDN'T WORK The next suspect is a blockage in the hose or wand. Disconnect the hose from the canister and the powerhead, and look through it. Also check the wand connection points and the suction slider on the handle—sometimes debris gets jammed there.
HEADS UP Never run this vacuum without the pre-motor filter installed. You'll let dust into the motor and cause a much more expensive shutdown.