The following steps require a Windows share (two separate local installs should behave closely similarly, but perhaps not identically). - open a document that is on the share from one computer (eg. the same one), - try to open the same file via the share from another computer, then choose to open the file in read-only mode, - click Edit Document in the infobar. => You get the following, rather uninformative dialog: "This document cannot be edited, possibly due to missing access rights. Do you want to edit a copy of the document? Open Copy / Cancel" Since the situation is same as before, a dialog with the same or close to same information should pop up (though perhaps the choices are different, since the file is already open). Observed using LO 6.4.0.0.alpha0+ (c2cb467a1e5194c56bb65706b7965fb2c9241b8f), 4.4.0.3 / Windows 7.
Mike Kaganski committed a patch related to this issue. It has been pushed to "master": https://git.libreoffice.org/core/+/60dffd80468e5ca4471bc67d02c58c8c784a86f1%5E%21 tdf#126241: make sure to fill input stream before LockOrigFileOnDemand It will be available in 6.4.0. The patch should be included in the daily builds available at https://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: https://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.
This can be closed as fixed I think, thanks Mike!