Error while executing Test Run: The default assignee does not have assignable permission or unassigned issues are turned off

While executing Test Run, we are seeing 'The default assignee does not have assignable permission or unassigned issues are turned off' error. To resolve this, follow below steps:

Select Project in which you are getting this error. Refer screenshots for steps :
Go to permissions by following steps in screenshot :
Grant permission to 'Assignable User' role by the following screenshot :
Now you will be able to execute Test Run