Unity 2019.1.6f1 'package manager UI' error. Missing 'package manager' and can't load new project

Unity 2019.1.6f1,
It occurs error that stop opening 'new project' when I create 'new project'

[com.unity.package-manger-ui@2.1.1]
[com.unity.timeline@0.0.0-builtin]
These two things make this problem as you can see.

I have found this 'manifest.json' file in the project folder 'project name > packages > manifest.json'.
 Open it with visual studio and I can see the line.

------->











I have edited those two lines like above image.
package-manger-ui 2.1.1 -----> 2.1.2
timeline 0.0.0-builtin       -----> deleted

After that, I can load the new project successfully and see the 'package manager' under 'Window' menu in Unity.