When attempting to add a Simple Java Add-In to ArcMap, the following error is returned and the Add-In does not load:
No GUI components found in this Add-In. Add-in version does not match.
This issue has been reproduced in both ArcGIS Engine and ArcMap versions 10.6.x and 10.7.x
This error occurs in the following software environment, under the conditions described below.
The Eclipse environment is configured to work with Esri ArcObjects and the ArcMap Add-In Project template. The error is returned when opening a new, blank map in ArcMap and attempting to add the DesktopAddin.SimpleAddin.esriaddin file.
The workaround for this issue is to load the Simple Java Add-Ins manually, using the following steps: