QUESTION:  Getting a Microsoft .NET Framework error when opening the Place Custom Abutment/Pier cell dialog.  

ANSWER: If you try to open the Place Custom Abutment (or Place Custom Pier) tool in a new file without an active bridge, you will see an informational dialog stating that no active bridge is selected. 

If you click OK, and proceed to click on the ellipses, to select the cell for the custom abutment, you will get below .NET Framework as shown above.

  

To resolve the issue you need to have an active bridge so that you can place an abutment or place a new bridge it it is a new/blank file.

NOTE: In a future release, a check will be added to the software to determine whether an active bridge exists in the file.

To Set an Active Bridge, follow the instructions in the KB article in the link below:

https://bentleysystems.service-now.com/community?id=kb_article_view&sysparm_article=KB0043347