Hello,
when creating a backup, is there a limit on the number of messages per contact and group?
On my mobile (iOS 15.5) with DC version 1.30.1 all the messages are there, but on the desktop (macOS 12.4) a group is missing the oldest ones.
Tried it with both version 1.28.2 and 1.29.1. The backup is of course up to date.
If it’s not normal, maybe it’s because I temporarily added a non-DC contact as a test? Only the history after the contact was removed is displayed on the desktop.
There is no limit on the number of messages in the backup. Backup is simply a copy of the database as used by the client, so if message is displayed in the client, it also goes into the backup.
OK, that’s weird. 
I just created a new backup on my cell phone and then imported it into the desktop version.
Some of the mails simply weren’t transmitted.
maybe…
This is unrelated, that bug is about deleting messages on IMAP server, not in the Delta Chat database.
What happens if you backup from desktop again and restore on the phone? Maybe the problem is that Desktop does not display some messages that are in the database?
The problem is solved!
DC really does transfer the whole chat-history to the desktop.
I can access the old messages using the search function.
Because I temporarily added a non-DC contact as a test, DC no longer fully recognizes the history from the backup, but only the new or the old part.
When I jump to the old one using a search, I can only scroll down to the point at which the contact was added.
After a restart, only the new one is displayed again. So the part after removing the contact.
I deleted the non-DC contact’s messages on the phone and made a new backup.
Now DC desktop recognizes all chat history again. 
This sounds like a bug, but I don’t understand the steps needed to reproduce this. You already had a chat with some contact, then copied a backup, then you added a contact (again? how?) and all new messages after that went into a new chat, unrelated to the previous one? And previous chat disappeared and can only be found in the search?
Does this bug sound like something related?
I added an email address to an already existing group.
Just to see what happens if you add someone who doesn’t use DC to a DC-group.
It worked quite well. The encryption was of course lifted.
Then I removed the address and the group continued as normal.
When scrolling through the chat history in the desktop app, I noticed that the oldest messages in the group were missing.
But they were present on the mobile phone.
I made a new backup and imported it into the desktop app.
However, the oldest messages were still missing.
So I suspected that maybe only a limited number of messages are backed up.
I think that used to be the case with WhatsApp.
Then I searched for one of the missing posts in the desktop app by simply typing in an old one.
The search was successful.
All the messages were probably there, but the old ones weren’t displayed.
I used the search function to jump to the appropriate place in the history.
Then I scrolled through the group chat. But now the more recent posts were gone.
After restarting the app, only the newer messages were displayed again.
So you could only see either the messages before the address was added or after it was removed.
I deleted the messages that were written in between on the phone and created a new backup.
After the import, the entire history of the group was visible again, except for the deleted messages, of course.
When you added a non-DC address to the group, Delta Chat was already installed on both mobile and desktop? Seems desktop decided it was a new group and started adding all the following messages there. Old messages probably remained in the old chat that went down in your chatlist, but was not gone.
Yes.
I assume so too.