Not able to add a subtask in Jira Software

[Mohammad Asif]

Hey I am getting below error while trying to add a child issue to task. kindly help me to resolve the issue

[Tansu Akdeniz]

Hi @Mohammad Asif 

Welcome to the community.

When you go to Project Settings -> Details page, there is a default assignee in the bottom. If selected option is the project lead and project lead doesn't have an assignable user permission (can be found under Project Settings -> Permissions), it may lead a problem.