[Bug 1.12.0]: Can't load campaigns from 1.11.5 and before.

[aliasmask]

Describe the Bug

My most recent campaign save:

An older campaign save:

Craig mentioned protobuff changes.

To Reproduce

Install 1.12.0.
Load an existing campaign.

Expected Behaviour

Expect my campaign to load without error.

Screenshots

No response

MapTool Info

1.12.0

Desktop

Windows 11

Additional Context

No response

[hmarcbower]

Similar error loading a campaign file that does load in v1.4.5.4.

Campaign File (272MB): https://www.dropbox.com/s/cpbw260aotk70ym/PoA%20for%20MT.zip?dl=1

Windows 10

[cwisniew]

@aliasmask do you have a small campaign you can share that demonstrates these two problems?

[aliasmask]

I took one of the campaigns and delete maps checking to see if error is still there until I got a reasonable size.
test 1.cmpgn.zip

[aliasmask]

I did the same thing with my other campaign. I narrowed it down to 1 map, City Map.
test 3.cmpgn.zip

[cwisniew]

I have a solution for two of the problems, the first (AbstractTemplate) one is proving to be a little trickier and will need to wait for tomorrow

[Phergus]

Tested. Supplied campaigns now load without error.