More than a week without reply or activity. Due to the policy of the tracker archiving for until required info/data are provided.

Thanks for the report, but blender 2.79 won’t get any fix in that area. Can you please check if 2.8 also shows same issue?

Just noticed that I've uploaded wrong .blend.
Corrected with one that does the thing.

Oh! Ok, That's important. I'll contact you if I have to report a crash bug.

Thank you for the report. Currently we are aware of many issues in 2.8 and actively working to fix them. But since replying to reports takes time, we have decided to limit bug reports to crashing bugs only at this point in time.

Putting this on normal (so it doesnt appear untriaged...) because there is an issue [but only with old dependency graph...]

not an issue if you use the new dependency graph
(run blender from the commandline with the --enable-new-depsgraph option)

About the situation with subsurf and no 'use modfiier stack', not it is clearer to me. The reconnect in this case seems to work like this:

@Philipp Oeser (lichtwerk) Yes, of course. Sorry in case I failed to follow the preferred procedures. No secret that I'm rather new around here.

Hi @Brecht Van Lommel (brecht), @omgold (omgold), I've seen you discuss this on the mailinglist (and I understand reaching out here as for some reason this report seemed to slip under the radar)
But: why not continue here? This way others (including me) can follow and participate much better.
Sorry for the wall of text, but pasting from the mailinglist, so it doesnt get lost...

sorry for the duplicate and thanks for the answer :)

Unfortunately operations that alter topology are not supporting Custom Split Normals:

The problem here is that the "Use Modifier Stack" setting is not properly taken into account for these disconnect/reconnect operators.

In T55210#505645, @LazyDodo (LazyDodo) wrote:

Thank you for the report. Currently we are aware of many issues in 2.8 and actively working to fix them. But since replying to reports takes time, we have decided to limit bug reports to module team members.

Thank you for the report. Currently we are aware of many issues in 2.8 and actively working to fix them. But since replying to reports takes time, we have decided to limit bug reports to module team members.

commited rB69f2305415a2

@Philipp Oeser (lichtwerk) : your work here is really aprecciated - thanks again for taking the time to fix this issue so soon!

@Lukas Ziechmann (bl_cat): note this isnt commited to master yet (want to check on an issue in 2.8 first so the merge would go smooth ...)
reg. T54397: surface deform is now ported as well, but changes can happen later as well [just need proper handling of 2.79 vs. 2.8], lets stick to that report and continue discussion there

*wow* - getting back from work to find the bug I reported yesterday to be already fixed for 2.79. Thank you so much @Philipp Oeser (lichtwerk)! Regarding my other bug report: T54397 , do you think I should CC a 2.8-developers directly as the surface-deform modifier isn't ported over to 2.8 yet or would that be considered annoying/ unhelpful? I don't know the policy here and I don't want to clutter their chat with unimportant messages. Thanks again for your time and effort!

LGTM

missing NULL check

lattice was already ported (see T54737), so this will need to go into 2.8 with minor tweaks separately

this probably wont merge into 2.8 cleanly [DerivedMesh → Mesh conversion], I guess I'll have to make another version for 2.8 as well [which should only be minimal massage].
CCing @Sybren A. Stüvel (sybren) , just so he knows...

D3239 should fix this

similar to rB9c95fd0a988fcd14f050098385e5461e2e51100d

Will have a look shortly

commited rB288d7794d4c6

possible fix: D3199

Just thought this could go in before this modifier gets ported in 2.8?

I'll leave porting the Particle Instance modifier to @Philipp Oeser (lichtwerk) then ;-)

@Sergey Sharybin (sergey): got it working, will post patch tomorrow (just saying, so @Sybren A. Stüvel (sybren) is not porting this modifier over in 2.8 before we merge?)