[BUG] Files in child elements of Entity are missing in Upload/Download of .aasx package

[ChristophRh]

Description
In an .aasx package, I have an AAS with a Submodel Element File (containing some file) as Submodel Element of an Entity.

1. Uploading this .aasx package in BaSyx Web UI reports:

Error uploading AAS!
Status: 404
Message Type: Error
Correlation ID: ElementDoesNotExistException-404
Timestamp: 2/13/2026, 4:36:33 PM
Text: Element with Id FileTest.my_File does not exist

(In case of basyx.backend=InMemory the last line Text: ... is missing in the error message.)

The file reference in Submodel Element File is present, but the file itself is not available.
Downloading the file via BaSyx Web UI reports:

[
  {
    "code": 404,
    "messageType": "Error",
    "correlationId": "FileDoesNotExistException-404",
    "text": "Requested File inside the Asset administration shell or File SubmodelElement with ID : File at path '/tmp/basyx-temp11767417251970391670/aHR0cHM6Ly96ZW1hLmRlL2lkcy9hYXMvc3Q4L2ludGVsL251Yy9zbS9zYm9t-<Path-To-File ... Filename.json>' could not be found. does not exist",
    "timestamp": "2026-02-13T05:32:18.180007366Z"
  }
]

2. Manually uploading the missing file to the File child element of Entity works fine.
   BUT downloading this fixed AAS using BaSyx Web UI results in an .aasx package not containing the previously added files.

Expected behavior
No vanishing of files.

BaSyx:

• BaSyx Version: latest off-the-shelf components (2.0.0-SNAPSHOT)
• BaSyx Java

BaSyx configuration

• Default getting-started configuration
• basyx.backend=MongoDB as well as basyx.backend=InMemory

System:

• OS: Windows 11
• CPU architecture: x64
• Browser: Brave (Chromium)

Note
Could be related to an already fixed issue regarding Submodel Element Entity: Missing Handling of Entities When Adding SubmodelElements

[aaronzi]

Thanks for reporting this issue. Seems like this was forgotten in the implementation since this is probably an edge case. Is there any official Submodel Template where this would be an issue or does this only happen for your specific case?

[ChristophRh]

In the Submodel Template "Software Bill of Materials" this is an issue, since it contains a File as Submodel Element of an Entity.
This Submodel is still marked as "In Development" on the IDTA website.
As I remember it was developed via the Interopera project and there was a download link on the project website (https://interopera.de/) which is not accessible anymore.
My last info was that the Submodel is in review process, but that was a long time ago...

[aaronzi]

Ok, I will find it in the IDTA share point. Thanks for the tip :)