Hi @Islam Ziane, thanks for your post! We usually see this when the email address you are trying to change to is already in use (likely by a user outside of your account). I would recommend checking this with the user in question. 

If this is not the case, please try making the change in a private or incognito window.

If the issue still persists, it’d be best for you to submit a support ticket here, as further troubleshooting will likely require some sensitive information. Thanks!

hey Eric, thank you for your answer, BUT :
i did try with email that i am sure that hasn’t a Lucid account. and tried also in multiple navigators and incognito tab. seems like it’s somthing else.

Thanks for checking that! In this case it’d be best if you submit a support ticket here, as further troubleshooting will likely require some sensitive information. Thanks!