Access denied. You do not have permission to perform this action or access this resource.

[Jeyganesh]

We are added the external user in our SharePoint online particular site. Also we provided the "Contribute" permission for that external user. The external user can access those site but they cannot access the list and libraries. if they tried it will be show the following errors. How to solve this issues?

[#2]

@Jeyganesh since your user has access to the page, kindly ensure that your list and libaries doesnt have a unique permisssion.

[#3]

1. Did you add them to the site permissions?
2. As Deahmeey said, do the lists have unique permissions.
3. It could be the contact list type, since it might be trying to access "Org assets" it coudl be causing it, do all the lists / libraries give this error? If so, seems like you might have added them to a page and not the actual site itself. You could also try adding them to one of the SharePoint groups such as 'SharePoint visitors" as well to correct that, assuming your permissions on the libraries and lists didn't remove this group.

[#4]

Thanks, I found the solutions

In other site list value picked from this list using lookup field  there is no permission for this user. 

so i provided the permission to source value list and solved the problem

[#5]

Access denied