The use of taking (an) interest

Is the following question correct?

What's wrong with taking interest?

I know taking AN interest or showing interest is better, but I would like to know if taking interest is also correct.

Solution 1:

There is nothing wrong with "taking interest". Interest can be used as a singular countable noun or as a mass noun with the same meaning:

• [ S or U ] the feeling of wanting to give your attention to something or of wanting to be involved with and to discover more about something:

  • I've always had an interest in astronomy. He never seems to show any interest in his children. Unfortunately, I lost interest half way through the film. She takes more of an interest in politics these days. informal Just out of interest, how old is your wife?

Cambridge Dictionary

From E-English Grammar:

• Gradually the children start taking interest in drawing and in course of drawing can learn a lot of things and can fair in their classes as soon as they are admitted to school in the nursery classes. When it is confirmed that the children are taking interest in learning, the parents should be more attentive than it is proper to teach ...