Spontaneous unsaved annotation loss

[meteorquake]

I've not managed to nail this yet so hopefully people might have experienced it and can chip in.

When I am doing annotations, but they are not yet saved, and focus on something else and focus back, (or possibly even scroll some distance), when I go back quite often (many times! including just now) all the new unsaved annotations are gone. I presume the file has refreshed itself, even though the source file has not changed. But it doesn't do it every time and I don't think it's entirely related to file size, so at the moment its occurrence is not something I can define in a reproducible way. The occurrance just now was on a small file on an NTFS share W10/64 to W10/64 viewed over Remote Desktop (mstsc.exe).

Perhaps this description might raise some ideas as to what could be going on...

3.6.16779 W10-64bit

d

[GitHubRulesOK]

Editing PDF is volatile, Hence Acrobat and many readers lock the file against concurrent access or edits.

SumatraPDF differs in that it does not stop file corruption for files under 32 MB, This is historically tied to the need for PDF-LaTeX editors to recompile (rewrite) the whole PDF whilst previewing the edits. The R key is for manual refresh/rebuild but auto refresh is possible.

The downside is that any other file related app can affect that temporary instability. If SumatraPDF has edits pending and any other file based app alters the contents appearance (annotations are most prone to such signals) then the new file index may become corrupted.

The worst place to be editing a file in such cases is outside a personal local folder (NEVER One Drive or other syncronised remote folder), thus I avoid edits on USB/ thumb drives or NAS or mapped drives like V:\... it is "risky".

[meteorquake]

Many thanks - I should clarify, the unsaved annotations disappear when the file is not being used in another program, so it's a case of disappearing without apparent reason...

[GitHubRulesOK]

small file on an NTFS share viewed over Remote Desktop

"is Volatile"
the data link is potentially prone to disturbance. That would be my equivalent to using V:\ which is another PC with its own antiviral monitor potentially altering my files stability. I will copy from V: to C: for edits.

[meteorquake]

I'll keep an extra eye on whether it is happening on a local NTFS drive - d

[meteorquake]

Also, perhaps I could set "ReloadModifiedDocuments" to false and see if it stops, though it may not if it's a necessary rebuild...

[meteorquake]

Thinking further it's also occurring on a RAM drive (ImDisk) with NTFS format (viewed with a remote viewer). Lots of variety to consider! I'll hopefully update in a few days on the matter.

[GitHubRulesOK]

@meteorquake
I was reminded that earlier 3.5.2 had a MuPDF incremental issue but that should have been fixed. #3981

However the same principles always apply that if a source PDF is unstable then the incremental saves are potentially like a tower of cards at risk of crashing later. This is most noticeable with some iOS/Apple annotations (so not just MuPDF but any PDF annotator using that Adobe additive method)