Hundreds of workers at Twitter have apparently turned down Elon Musk's demands to sign up for "long hours at high intensity".
Its office buildings, including the base in Dublin, are now closed until Monday.
Reports suggest the platform's new owner fears "sabotage".
There are also fears the technical viability of the site could also be at risk, as hundreds of engineers jump ship.
Legal questions are also mounting around employees' rights, just weeks after it laid off around half of its workers.