It means your master cylinder needs to be replaced or rebuilt. The seals inside the cylinder can go bad and cause this to happen.
Bad master cylinder.
No, it more commonly causes soft braking.
how do i know the master cylinder is bad ?
Air in a brake line or a bad master cylinder could cause this. Bleed the brake lines if you have been working on any brake cylinder. If this happened without any warning, the master brake cylinder is probably the cause and should be replaced.
a leak or a bad master cylinder
This could be caused from the closing off of the flex line or a bad caliper or a bad master cylinder
The gasket to your clutch master cylinder is probably broken or cracked. or your master cylinder is bad.
Normally this is caused by a Master Cylinder that has failed. Replace the Master Cylinder. Normally this is caused by the loss of fluid in the brake system. The fluid reservoir needs to be checked first. It possibly may be caused by a bad master cylinder but the most common cause is loss of brake fluid.
Look for leaking fluid at the slave or master cylinder.
You've either got a bad Brake hose or bad master cylinder. Both these things can cause a caliper to stick.
If the master cylinder reservoir is empty, you have a leak somewhere. If the master cylinder reservoir is full, the master cylinder is bad.