For the uninitiated, read-only is an option that prevents a file from being changed or overwritten. When opening a SOLIDWORKS file, for example, sometimes you will experience the file are in read-only mode.
For this one, whenever you try to make change to this file, it will prompt to save as every time you click the save document. It’s important to note that opening a SOLIDWORKS file using this method does not prevent you from making changes or overwriting the file. Instead, a message dialog will appear upon saving informing you of the document’s read-only status.
To solve this issue, just can click at the Option > System Option > External References and tick at the Don’t prompt to save read-only referenced document
Then can close SOLIDWORKS and re opened the file again.