I can't access Le Bon Coin!

Hello, sorry for the delay in responding.
Thank you for your help
But I went to check and unfortunately it's not from there, everything is checked.
What's strange is that it's the only site that's causing problems.
In any case, thanks again.

Hello,

What does it give with another browser, whether it's IE, Google Chrome, etc...?

--
Human beings are at their best when things are at their worst.

Try resetting Firefox.

Launch Firefox
In the address bar, type --> about:support and hit enter
Click on --> Refresh Firefox

--
Human beings are at their best when things are at their worst.

Hello and thank you very much for your help
It took me a few days to find enough time to do this operation and reload Mozilla.
Unfortunately, the problem is not resolved.
Instead of "establishing a TLS connection with comptepro," I now have "establishing a TLS connection with static-rav." At one time, when I could connect to Le Bon Coin randomly, I noticed that as soon as it displayed "establishing a TLS connection..." at the bottom, it was doomed; when I can open a page on Le Bon Coin, it shouldn't show this at the bottom.
With IE, nothing works, it doesn't open any page, but I think older versions of IE are working less and less...
Would it be worth trying with Chrome?
I'm afraid of messing up my computer by trying to download it...
Thanks in advance for your help.

Download and install --> MalwareBytes

Run it as administrator
Go to settings
Account tab
Uncheck the box --> Disable Premium trial
Update it
Scan now
After the scan
If positive, click on --> Quarantine all
Restart the pc.

--
Human beings are at their best when things are at their worst.

Is Windows up to date?

I suggest you uninstall Firefox and reinstall it properly.

Go to Start
Control Panel
Folder Options
View tab
Check --> show hidden files and folders
Apply and OK.

Then, Programs and Features
Uninstall Firefox (including the profile)
Restart the PC.

Go delete the mozilla folder in these 3 directories:
--> C:\users\your username\AppData\Roaming
--> C:\users\your username\AppData\Local
--> C:\Program Files (x86) and/or Programs

Delete the Firefox shortcuts on the desktop.

Reinstall the desired version:
--> Firefox 64-bit
--> Firefox 32-bit

--
The human being is at its best when things are at their worst.

Hello and thank you very much for your help.
Indeed, I should have thought of trying with IE....
and it works but with a display format that is not the right one; on the first attempt it didn't work at all, the page wouldn't load while I could open other sites without a problem, and after several attempts it works, so the issue might be with Mozilla??
The fact that there are errors with IE could be due to the fact that I'm still on Windows 7, which is probably nearing the end of its updates.....
Best regards

Hello and thank you again
I also did this without any result.
Now I can no longer access Le Bon Coin at all, but why only this site????
And it says at the bottom left of the screen "establishing a TLS connection with comptepro leboncoin.fr", while I don't have a pro account.

I finally just loaded Chrome and.... it's the same....