I also got this problem after importing a Word “.doc” file with some embedded form objects ( check boxes ).
The file opens up just fine in Word, where I can check and uncheck the check boxes and edit the content with no problem.
But after importing and loading it into LibreWriter, the status bar showed “read only” and when trying to edit the contents a message popped up saying “Write-protected content cannot be changed, no modifications will be accepted”. Check boxes could still be checked / unchecked, though.
The solution involving sections ( “Format” → “Sections” ) didn’t work, because it was grayed out ( → no sections ).
Finally, the solution that worked for me was the one about “protected form”:
- Go to “Tools” → “Options”
→ “LibreOffice Writer” → “Compatibility” → “Protect
form” - Make sure the “Protect form”
option is unchecked.
Now you can check / uncheck the check boxes and edit / modify the contents of the document.
( Using LibreOffice 5.1.6.2 and Ubuntu 16.04 LTS )