Hi, I recently had the same, three times.

It is dutch, “During loading Obsidian an error has occurred”.
After this I’ve tried both options, both resulting in the following two screenshots:

This message is show in the top of the screen, while a (last time opened) mdfile is loaded and shown.
“Obs indexes the vault…This happens only once. Certain functions are not available until this is completed.”

“Indexing is completed.”
The first 2 times it started with the shown error.
Third time it didn’t show the error, only the indexing.
Result:
All md files look correct.
Yet, all backups are deleted (in standard plugin File Recovery). I might overstepped myself here, I set the amount of days to ~9999999. I would like to keep it on a long term for comparisons.
Possible causes:
First time: battery died; during booting the phone, I also opened Obsidian, perhaps it couldn’t create a snapshot of the loaded file (on time/in time, perhaps a time threshold), due to the load of the system while booting.
Second time: Google’s Playstore app is updated, available internal memory went to a low. I opened Obsidian from a sleeping instance/process, but vault had to be reloaded and then the error occurred.
Third time: unbeknown to me, alas.
Android version:
Version 1.4.1 (83)
API v1.0.3
No usage of community themes/plugins.
Extra question (perhaps for the devs):
Are the backup files in fact deleted? Does it free up the internal memory of the phone?
(I can’t see the location of the files, couldn’t find the system directory Sys dir with my app Total Commander, phone is not rooted etc.).
Note:
I know, I have to update to current version of the mobile app.
But perhaps it can still be mitigated even for newer versions, in order to prevent the result of loss of the snapshot/backup files.
In the near future I will update the app and check if it still occurs. If so, I will report it in the bugsection (with #Mobile? #Android?).
Thanks in advance,
Best regards,
Quorkie