How to solve a "Data of manifest.rdf" problem?

Hello I am running:
Libre Office Version:
Build ID: f82ddfca21ebc1e222a662a32b25c0c9d20169ee
CPU threads: 4; OS: Linux 4.15; UI render: default; VCL: gtk3;
Locale: en-CA (en_CA.UTF-8); UI-Language: en-US
Calc: threaded

On Linux Mint 19,3 Cinnamon 64 bit

Working in LibreOffice Base with a split database, I have taken much time to create forms in a database and today, received this message when attempting to open each form in the database:

“Data of manifest.rdf could not be read.”

On answering Ok. I receive this message:

The document “TITLE OF DOCUMENT” could not be opened.

SfxBaseModel::loadFromStorage: 0x50070b0f

I cannot open the reports I have created either. I get the message:
“General Error”

Is there anyway I can retrieve the forms and reports I have created.
I note that the Queries and Tables in this database are still accessible and can be copied.

I have looked for a solution for this but do not find an answer. Can anyone help me?

I’ve just experienced the same problem.

Version: / LibreOffice Community
Build ID: 30(Build:2)
CPU threads: 12; OS: Linux 5.15; UI render: default; VCL: gtk3
Locale: en-NZ (en_NZ.UTF-8); UI: en-GB
Ubuntu package version: 1:7.3.7-0ubuntu0.22.04.1
Calc: threaded

The database is a MariaDB connected by JDBC.
I have looked at several instances of the manifest.rdf files embedded in the .odb archive, and they all look perfectly readable.
I can’t find a solution anywhere in the forum. Is there any new information on this issue please?

manifest.xml should show the path to all content in the Base file.
Every form will contain a manifest.rdf. This manifest.rdf seems to contain the same information in every form.
manifest.rdf links to content.xml and styles.xml in every separate folder for a form.

I would use a backup file of the database file if original doesn’t work.
If there isn’t a backup file I would install LO direct from, not from a Linux distribution. Have installed many versions of LO parallel to the version OpenSUSE installs by default on my system.
If none of the forms will appear I would try to create external forms from the internal forms/Obj… folders by using an empty Writer file for a form.

Thank you for your prompt reply Robert.
As you can see, I’m running the latest production release of LO.
I can see the forms listed, and a short while ago they opened OK.
Now they don’t open in either entry mode or edit mode.
I will try creating a new form and see how it goes.
Many thanks for your help