The cause of the mentioned problem is incompatibile code with installed tensorflow library. In this case you have code compatible with tensorflow 1.0 version but installed tensorflow 2.0 or higher. Let's see what you can do to solve the problem.
Continue Reading [SOLVED] – AttributeError: module ‘tensorflow’ has no attribute ‘placeholder’
Unresolved reference issue is one of the most common problems that novice programmers face. The following article describes possible causes and solutions for the issue.
Continue Reading [SOLVED] – PyCharm: Unresolved reference issue