The phrase "endless attempts" is correct and usable in written English
It can be used to describe a situation where someone is making continuous or repeated efforts without success.
Example: "Despite countless endless attempts to solve the problem, we still haven't found a solution."
Alternatives: "countless efforts" or "ceaseless tries"
Keeping at bay endless attempts by the NHS to downgrade Epsom hospital, and the Conservative green paper on welfare reform.
Wilson's endless attempts to reach an accommodation with Ian Smith's Rhodesia ended in fudged deals culminating in UDI.
In fact, Judge Frost noted, in Ohio's endless attempts to seem like it's fixing errors and inconsistencies, sometimes "state agents lie to the courts".
The whole of this splendid book is about weather that is inhuman and also about language that is human, making endless attempts to understand weather.
The Proscenium arches, marble-inlay tombstones, and manically ornamented everything are an incredible testament to the Knights of St John's endless attempts to keep up with the Medicis.
We were panicky when a strange car pulled up near us or a camera flash went off, but despite endless attempts, the press just didn't catch on to a remote resort in Austria.
"What concerns me about the American press is this endless, endless attempt to label the guy some kind of kook not fit to be President," he said.
If Ahab's monomania in Moby Dick centres on the pursuit of a whale, then the Everton manager's weakness is his seemingly endless attempt at replicating Guardiola's Barcelona model.
Cathy provides another chance for Linney to explore a complicated character, to take a forensic look beneath a life that has, for years, comprised an endless search for the perfect couch, and an equally endless attempt to keep a sweet-but-shallow husband, and an over-indulged son, fed and happy.
A Sheriff, who in his endless attempt to try to humiliate male immigrant detainees, has mandated that they wear pink underwear.
the centerpiece of Major League Baseball's endless attempt to rid itself of the stigma of its very own superstars cheating their way to the upper echelons of on-field statistical success, was finally sentenced to 211 games of suspension from his sport, without pay.
