I’m going to ask you to post some additional information that might help us to identify the problem.
Please do this:
- Close all Arduino IDE windows.
- Start the Arduino IDE.
- From the menus, select Tools > Board > Boards Manager
- Wait for the updates to finish.
- Attempt to install the “Arduino mbed-enabled Boards” platform, as before.
- After you get the error message, click the “Close” button.
- Click on the black console window at the bottom of the Arduino IDE window.
- Press Ctrl+A to select all the text.
- Press Ctrl+C to copy the selected text to the clipboard.
- Paste the copied text into a reply here, using code tags (</> button on the toolbar).