Micro Focus Enterprise Developer 3.0 for Visual Studio 2017 > Welcome > New Customers: Where do I start? > Upgrading to Enterprise Developer for Visual Studio > Differences between Enterprise Developer and Net Express and Mainframe Express > Run-time System Differences > Enterprise Developer Co-existing with Earlier Micro Focus Products

Enterprise Developer Co-existing with Earlier Micro Focus Products

If you have Enterprise Developer and Net Express or Studio Enterprise Edition installed on the same machine, you sometimes receive a run-time system error if either the COBCONFIG or COBCONFIG_ environment variable is set when you run Enterprise Developer applications the configuration file it refers to contains entries that are not valid for Enterprise Developer.

To work around this issue, ensure that Enterprise Developer is not running and then modify the configuration file by doing one of the following:

If the invalid tunable is not needed by another application, remove it from the run-time configuration file.
Add the following as the first line in the configuration file:
```
set cobconfig_error_report=false
```
Unset COBCONFIG (or COBCONFIG_) or set it to another configuration file that does not contain the invalid tunable for the particular session you are running in.