Commented Unassigned: Multiple NetOffice Excel Add-ins [21946]

Hi,

I am currently having a problem with 2 excel add-ins built with NetOffice version 1.6 and 1.7.2. These two add-ins are being developed on the same machine The second add-in that loads (loading seems to be based on the addin progid, and then in alphabetical order) will throw an exception in the __IDTExtensibility2.OnConnection__ method. The method looks like this:

```
void IDTExtensibility2.OnConnection(object application, ext_ConnectMode connectMode, object addInInst, ref Array custom)
{
try
{
this.excelApplication = new Excel.Application(null, application);
...do some work...
}
catch (Exception exception)
{
...
}
}
```

The exception is thrown where the new '''Excel.Application''' is being created. The message of the exception is the following:

_Object reference not set to an instance of an object._

Does anybody have an idea what may be the cause of this problem? Could the problem be that the two add-ins do not use the same version? one is using version 1.6, the other is using version 1.7.2.
Comments: ** Comment from web user: ajvorobiev **

Dear Sebastian,

updating all plugins to 1.7.3 (latest available Nuget) and having them initialize each their own Cores did not help our problem. Addins still somehow interfere. One of the clues that I am leaning towards is the use of ICustomTaskPaneConsumer and ICTPFactory in at least one of the addins. If this addin is the second to load, its task panes cannot be found. No particular exception is thrown, just the taskpanes are not created when the addin loads.

I hope that you can further investigate this issue.

Kind Regards,

Alex