The biggest strike to hit Paris public transport in more than a decade disrupted tourists’ plans and forced commuters to work from home or find alternative ways to reach the office.
Unions are protesting against plans for a sweeping pension reform by French President Emmanuel Macron’s government.
Paris public transport company RATP said 10 metro lines were closed and several others, including the RER suburban rail, severely disrupted.
Bus and tram schedules were also affected.
On platforms, messages in French and English warned passengers of the strike, the biggest since 2007.
Trains that were still circulating were noticeably less crowded than usual, as authorities advised people living in the Paris region to work from home or choose other means of transport.
The government website monitoring roads showed major traffic jams at rush hour Friday morning in and around the French capital.
Many Parisians and tourists could be seen using city bikes and electric scooters, or simply walking.
RATP employees are protesting against a pension reform planned for next year that is expected to make them work longer before retirement.
At Le Vesinet, west of Paris, commuter Benjamin Royoux said he was “rather pleasantly surprised” to find that there were trains every 15 minutes.
But Mr Royoux, who uses his electric scooter to circulate in the Paris city centre, was worried that there could be more strikes.
“One day is going to be OK. But if it continues … we’ll see.”
Paris City Hall employee Catherine Reine, also waiting for her RER at Le Vesinet, said she supports the strike “because (transport workers) are very afraid for their future, and I think it’s normal.”
RATP employees are among workers from some specific professions who benefit from a special pension regime, currently allowing them to retire on a full pension earlier than most French people.
Mr Macron says the planned changes would make the public pension system “fairer”.
He has promised the legal retirement age will remain at 62 but new conditions will encourage people to work longer before retiring.
The government also wants to apply the same rules to all new pensioners in order to replace the 42 different systems specific to certain jobs.
A junior transport minister, Jean-Baptiste Djebbari, told reporters on Friday that “today there are several special regimes and one general regime that is not sustainable financially, everyone knows that”.
The reform will be formally presented and debated in parliament next year, following a three-month consultation with unions and employers’ groups.
Lawyers, who also benefit from a special pension system, are planning a strike on Monday.
Several left-wing unions are also planning demonstrations on September 21 and 24 in Paris over the pension reform plans.