When installing new packages or when loading the installed external-dependencies will be sometimes deleted up to the fiona folder (A-F). In the fiona folder a few files are deleted as well.
temporary workaround is to make a copy of the folder '%appdata%\3Di\QGIS3\profiles\default\python\plugins\hhnk_threedi_plugin\external-dependencies' and restore that copy when above errormessage occurs or other environment issues surface.
When installing new packages or when loading the installed external-dependencies will be sometimes deleted up to the fiona folder (A-F). In the fiona folder a few files are deleted as well.
temporary workaround is to make a copy of the folder '%appdata%\3Di\QGIS3\profiles\default\python\plugins\hhnk_threedi_plugin\external-dependencies' and restore that copy when above errormessage occurs or other environment issues surface.