This almost always indicates lack of air flow, which can be caused by:
A full bag.
Dirty or wet filters. At some point a filter can no longer be cleaned well enough and should be replaced.
A blockage in the hose or a tool. Take the hose or tool off and reverse the airflow. AFTER the blockage has been cleared your machine will need to cool down. This can take several minutes to a few hours. Watch out for a “hidden or hard to find” HEPA filter that needs to be replaced. FYI, no matter what some manufacturers tell us, HEPA filters can never be “cleaned” well enough. They should ALWAYS be replaced.