I am a new QGIS user. I have layer containing few polygons, imported from a .KML file (I have created them with Google Earth). I need to adjust the vertex, so I right click on the layer and select "enable modifications" (not sure how is the English label in the menu, I have Italian localized installation). Then I click on the "vertex tool (all vectors)" and I am able to move the vertex I need. When I want to save the changes I made, I click on the "save vector modification" icon, but I get this error message: "OGR error to set element 1: Failed to open C:/PROGRA-1/apps/qgis/./resources/data/world_map.gpkg: Permission denied". If I keep trying, I get a different error message: "OGR error to set element 1". Any suggestions?
Your first error may be from using the vertex tool (all vectors) - it may have tried to modify an underlying layer that you did not intend to edit (for example
world_map.gpkg in your error message).
Your second issue is due to the fact that you cannot perform most edits on KML/KMZ files in QGIS. Even though you can see the yellow pencil enabled which suggests editing, you can add features (albeit with some lag), but deleting or updating of features is not supported in OGR which is used to update the files in QGIS. Refer to this answer for a brief explanation: Why can't I edit KML/GML layers? (8 years ago)