Clear the cache and remove cookies only from websites that cause problems.

"Clear the Cache":

• Firefox/Tools > Options > Advanced > Network > Cached Web Content: "Clear Now"

"Remove Cookies" from sites causing problems:

• Firefox/Tools > Options > Privacy > "Use custom settings for history" > Cookies: "Show Cookies"

See also:

• http://kb.mozillazine.org/Cookies
• https://support.mozilla.org/kb/Deleting+cookies

Is your question how to transfer cookies from Firefox installation #1 to Firefox installation #2?

If you are asking how to create a cookie from scratch that the website will view as valid, I am not aware of any way to do that.

cor-el said

Clear the cache and remove cookies only from websites that cause problems. "Clear the Cache":

• Firefox/Tools > Options > Advanced > Network > Cached Web Content: "Clear Now"

"Remove Cookies" from sites causing problems:

• Firefox/Tools > Options > Privacy > "Use custom settings for history" > Cookies: "Show Cookies"

See also:

• http://kb.mozillazine.org/Cookies
• https://support.mozilla.org/kb/Deleting+cookies

the problem is when i try to log in to my facebook account it ask me to log in from a recognizable device when the only device i have now is my Pc which have a new windows. so i ask if is there any way to make my pc recognizable for facebook Bs" my account is not attached to phone number"

jscher2000 said

Is your question how to transfer cookies from Firefox installation #1 to Firefox installation #2? If you are asking how to create a cookie from scratch that the website will view as valid, I am not aware of any way to do that.

the problem is when i try to log in to my facebook account it ask me to log in from a recognizable device when the only device i have now is my Pc which have a new windows. so i ask if is there any way to make my pc recognizable for facebook Bs" my account is not attached to phone number

What browser are you using?

You can check for problems caused by a possible corrupted user agent.

See:

• https://support.mozilla.org/kb/websites-say-firefox-outdated-or-incompatible
• https://support.mozilla.org/kb/Finding+your+Firefox+version

Well, if it was easy to fake out Facebook by hand crafting a cookie, they probably wouldn't even bother with this security feature... Hopefully there is another way to solve the problem.