The Semaine Olympique Française - which was set to offer four qualification spots for the Tokyo 2020 Olympic Games - has been cancelled due to the coronavirus pandemic.
The annual race was scheduled to take place in Hyères in France from April 3 to 30, with World Sailing hoping for it to be the "highlight of the season" and a "key event" for Olympic sailing.
The last four European quotas for the laser class at the rescheduled Olympic Games were due to be awarded there.
The Finn Open and Under-23 European Championships was also set to form part of the four-week competition.
But organisers failed to secure the backing from France’s international delegation for major sporting events (DIGES), despite putting in place a series of coronavirus countermeasures.
World Sailing said the Organising Committee had spent almost a year drawing up a plan to ensure sailors were able to compete in a safe environment.
The event, which was part of World Sailing’s Hempel World Cup Series, was originally scheduled to be held from April 17 to 24 before a new version was proposed that would be held over four weeks in a bid to meet social distancing restrictions.
But it was not enough to win over DIGES while France battles to contain the spread of coronavirus.
"We made the difficult decision to cancel Hyères's 2021 Semaine Olympique Française following the response from DIGES," said French Sailing Federation President Nicolas Hénard.
"We studied all the ways we could guarantee an event that would respect health standards and guarantee all the athletes attending watertight health and safety.
"We hoped that this event, focused on sailors engaged in an Olympic programme, would obtain the necessary agreements, especially after re-planning it over four weeks.
"But at this point, due to the ongoing health crisis, we cannot hold this event.
"Of course, my thoughts also go out to the Organising Committee, our partners and our volunteers, who are so enthusiastically involved in making the event such a success every year.
"My thoughts are with the members of the French team too.
"They are experiencing a unique Olympic build-up.
"We were happy to be offering them a high-level home event ahead of the Olympic Games.
"Unfortunately, we'll have to do without it, but I'm sure they'll be able to bounce back and arrive in good shape in Japan this summer."
Vilamoura in Portugal has now stepped in to stage the Finn Open and Under-23 European Championships from April 10 to 16.
Balazs Hajdu, President of the International Finn Association, said: "We are very grateful to all those who offered to host our Europeans at short notice and are very happy happy to accept the proposal from Vilamoura in what is a very important period for many Finn sailors as they prepare for the crucial Finn Gold Cup in nearby Porto."
The virtual Semaine Olympique Française is scheduled to run from April 17 to 24 using Virtual Regatta - a digital sailing platform.
It will be the second time the virtual event has been held.
France has recorded 3.8 million cases and almost 88,000 deaths from COVID-19 since the start of the pandemic.