When editing an existing PDF file, I cannot use File > Export As PDF or using the Export feature, then choosing PDF as the file type and choosing to export with the original file name, and confirming to overwrite it. The error given is: Error saving the document : General Error. General input/output error. Expected behavior is to be able to overwrite the file I'm editing. Note, the PDF is NOT open with any other software at the time. It seems that LO is locking the PDF even from itself. Workaround #1: Export the PDF to a different file name. Delete the original file. Rename the new file to the original file name. Workaround #2: If PDF printing is available, through the respective print dialogs, such as on macOS "Save as PDF" or linux "Print to File", and choosing to overwrite - works fine. On Windows, this is not natively available, but does work with 3rd party PDF printers such as Bullzip. This bug was present in the 5.x series as well, I'm just getting around to reporting it now that I see it is still present.
*** This bug has been marked as a duplicate of bug 103947 ***