I need to make attachment field mandatory in one of the issue type of a project only if they choose 'Yes' in response of another custom field.
Is it possible to achieve ? If yes, please help with it.
Can be done with any number of addons. You should see what ones you have in your instance and which ones can provide a validator to do your check.
The basic idea is you want a validator that check if field 1 is set and if so, that there is at least one attachment.
What add-ons do you have to work with?
This is not possible to achieve in Jira out of the box.
You can make a field required based on input from another field using 3rd party applications.
There have been several discussions already created here which might help:
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