Muskmelons slip but not all cantaloupes are muskmelons. Could be you have a variety that does not slip or an oddball cross. Better possibility that the melon is damaged in some way

I've harvested 14 melons this year, from the same seed packet, and they all slipped, except this one. BUT, I cut into it. It was not sweet. In fact, it had kind of a bad taste. So we're not talking overripe. You can see in the picture below that the left hand side is damaged, and amongst the seeds in the center there is some white mold-like fuzz. But the melon was soft all the way around. Definitely a damaged melon. But there weren't any obvious holes in the skin. Not clear how the damage happened.

Did the vine it was attached to look healthy? If the leaf at the stem was dead or drying it could be a sign.

Not every living thing is perfect.

I just started harvesting my charentais melons, and so far all of them slipped except one. It looked ripe though, so I cut it off and it tasted fine, just like the rest of them. One of the mysteries of mother nature....

I'm not growing charentais melons this year, but last year I did, and none of them slipped. Allegedly, most aren't supposed to, but there are some varieties (e.g. Sivan) that do. Charentais are actually a honeydew-variety of canteloupe, without netting, and honeydews don't slip.

Dan, indeed they aren't supposed to but they do for me! I'm only growing hybrids through, so maybe their genetic makeup is different in that area? The French heirlooms were a disaster in my humidity.

I find Johnny's charts very helpful -- here' one on melons:

http://www.johnnyseeds.com/growers-library/vegetables/melon-comparison-chart-pdf.html

cantaloupes and muskmelons are not same thing even though they are related.

A little off-topic, but cantaloupes and honeydews (and Charentais as well), are all cultivars of muskmelon (cucumis melo).

Dan incorrect. muskmelon have netting and cantaloupe don't.

source "Melons for Passionate Grower." Amy Goldman

"Muskmelon (Cucumis melo) is a species of melon that
has been developed into many cultivated varieties. These include smooth-skinned
varieties such as honeydew, Crenshaw, and casaba, and different netted
cultivars (cantaloupe, Persian melon, and Santa Claus or Christmas melon)."

https://en.wikipedia.org/wiki/Muskmelon

"The most popular type of muskmelon in America is the small, oval,
heavily netted kind commonly called a cantaloupe. All cantaloupes are
muskmelons, but not all muskmelons are cantaloupes.

Muskmelons have a wide range of other forms, sizes, and flesh
qualities, such as the Honey Dew, Casaba, and Persian types; the large
Bender, Montreal, and such odd varieties as the elongated Banana should
not be called 'cantaloupes.'"

https://aggie-horticulture.tamu.edu/archives/parsons/publications/vegetabletravelers/muskmelon.htm

Cantaloupes don't have netting ??? The ones I grow sure do. The ones the stores sell sure do. These references sure think they do.