Issue Description
If an ARCHICAD project file was created in a copy of ARCHICAD which had add-ons, but the file is being opened in a copy of ARCHICAD where the add-on is not present, you will see the following dialog, followed by one or more listed add-ons and a checkbox next to each item.
Solution
If you wish to avoid seeing this, and you are certain the file does not need this data included in the file, you may remove the tick mark from the check boxes and click OK. Then save the file and this will remove the meta-data from the file and you will no longer get the Add-Ons window appearing when opening the project file. Check with the Add-on vendor if you are unsure of what impact this can have on your file. Another good idea is to save a copy of your file before removing the data, then you may validate that nothing important is lost before crossing a point of no return.