### **Environment**:

Your OpenProject Version: **OpenProject 10.3.0** (PostgreSQL)

Windows 10 / Firefox 71.0, Chrome 79/ Language: de

### **Logs**

No errors in browser console, No special warnings or errors in openproject's logs.

### **Steps to reproduce:**

1. Enable Backlogs
2. Create a parent WP with at least on child Begin of the insertionWP, all of type Task.End of the insertion Begin of the deletion WP.End of the deletion
3. Set a version for the parent. --> The version should correctly be inherited by the children.
4. Begin of the insertionChange the type of the parent to Phase 
5. End of the insertion Remove the version from the parent --> Child keeps its Begin of the insertionversion.End of the insertion Begin of the deletion version incorrectly.End of the deletion
Begin of the insertion6.End of the insertion Begin of the deletion 5.End of the deletion Try to change the version attribute of the child
Begin of the insertion7.End of the insertion Begin of the deletion 6.End of the deletion Error appears, that Version is locked

### **Actual Behavior**

* When the version of the parent is removed, the child keeps its version.
* Error appears, Version attribute cannot be changed.

### **Expected Behavior**

* Removing the version of the parent should Begin of the insertioneitherEnd of the insertion be inherited by the Begin of the insertionchildren, or the children should be editable.End of the insertion Begin of the deletion children.End of the deletion