Look at the example below:
The manager is having his problems (A)/ but we have (B)/ ours as well. (C)/ No error (D)
The site that I am following says:
The verb "have" can work as continuous and non-continuous verb depending upon its meaning. When we use it to mean as "experience", we can use it in continuous form. For example, I am having great fun now.
When we mean it to possess something, we cannot use it in continuous form. For example: I have a car. In this case, we cannot write it like I am having a car.
In the given sentence, "have" is used to means to possess the problems. So, it cannot be used as "having" and should be written as "have". So, the error is in part (A) of the sentence.
But how does someone possess a problem? We experience a problem as far as I know. Is it the phrase 'his problems' that gives a meaning of possession?