Redmine

+1!

Not sure about the fields "Category", "Start Date" and "End Date", as they may be different from the parent task. But for sure the field "Version" should be inherited, as it´s important to have the same version so the Gantt is displayed correctly.

+1 to inheriting the version.

+1

+1. This is useful. Also, if we combine this with #13561 - it would be very useful and neat.

For example, when you go by New issue you fill up the complete blank form. Where as when you go by 'Add sub-task' all fields come pre-filled.

However, this is not an ultimate solution. Nothing helps when sub-tasks has old information where as parent task is updated. See #13585 for more details.

+1
This is very useful. Every sprint we define the high level deliverable as a task, and then add the detailed subtasks assigned to individual engineers. Having this functionality will make subtask creation much more efficient for us.

+1
This is very useful. Every subtask it takes a lot of time to fill the fields

Fields:

Category
Target version
Customer
Sprint
Milestone
Features
External Ref

when adding a new subtask to Redmine, each of said fields is pre-filled with the parent's task values.

+1
This is very very useful for us, when adding a new subtask to Redmine, each of said fields is pre-filled with the parent's task values.

+1
Inheritance of the target version is a mandatory feature if You want to manage a project. Otherwise You need a check tool that checks if there are accidentally subtasks that have a different target version than the parent (that is dangerous!).

I recommend that the project settings allow to configure each tracker field if it will be inherited from the parent (if there is a parent).

However, inheritance should only be a default proposal. Of course there are use cases where it makes sense to have different target versions, e.g.:
consider three target versions:

|----target version intermediate----♢0
|----target version release 1---------------------♢1
|----target version release 2----------------------------------♢2

Legal

|----task-----------------------------------------♢1
  +----sub task A-------------------♢0
  +----sub task B---------------------------------♢1

Illegal

|----task-----------------------------------------♢1
  +----sub task A-------------------♢0
  +----sub task B----------------------------------------------♢2

You should checkout Subtasks Inherited Fields Plugin at https://github.com/edosoft/redmine-inherit-fields-plugin