Invalid DXF export after adding layers from another theme

[dominik-warch]

Exporting the map as DXF works correct when I only export layers from the current theme. As soon as I add layers from a different theme, the exported DXF is broken/invalid. Some software like BricsCAD can open them but others either can't open the file at all or show missing or empty layers.

[manisandro]

DXF is notoriously annoying to debug. Any helpful error message from the applications would be helpful.

[dominik-warch]

Helpful... I'm not sure. OGR shows this:

DXF: Read 9 header variables.
DXF: Read 15 layer definitions.
ERROR 1: /home/abuild/rpmbuild/BUILD/gdal-3.13.1-build/gdal-3.13.1/ogr/ogrsf_frmts/dxf/ogrdxf_blockmap.cpp, 98: error at line 20880 of bauverwaltung_20260708_153522.dxf
DXF: 14 features read on layer 'entities'.
DXF: Read 9 header variables.
DXF: Read 15 layer definitions.
ERROR 1: /home/abuild/rpmbuild/BUILD/gdal-3.13.1-build/gdal-3.13.1/ogr/ogrsf_frmts/dxf/ogrdxf_blockmap.cpp, 98: error at line 20880 of bauverwaltung_20260708_153522.dxf
DXF: 14 features read on layer 'entities'.
ogrinfo failed - unable to open 'bauverwaltung_20260708_153522.dxf'.

QGIS just tells me "not valid or not recognized data source", even with higher debug levels. Line 20880 is an empty line, I added the DXF below.
bauverwaltung_20260708_153522.zip

[dominik-warch]

FreeCAD opens the file but gives the following warnings (complete log):

16:14:31  Duplicate block name 'symbolLayer0' found. Ignoring subsequent definition.Duplicate block name 'symbolLayer0' found. Ignoring subsequent definition.Duplicate block name 'symbolLayer1' found. Ignoring subsequent definition.Duplicate block name 'symbolLayer2' found. Ignoring subsequent definition.Duplicate block name 'symbolLayer3' found. Ignoring subsequent definition.Duplicate block name 'symbolLayer4' found. Ignoring subsequent definition.Duplicate block name 'symbolLayer5' found. Ignoring subsequent definition.Duplicate block name 'symbolLayer6' found. Ignoring subsequent definition.
--- DXF DRAFT POST-PROCESSING ---
16:14:31  --- Draft post-processing finished. ---
16:14:31  
--- DXF import summary ---
Import of file: '/home/gv14/Downloads/bauverwaltung_20260708_153522.dxf'

DXF version: AC1018
File encoding: iso-8859-1
File units: Unspecified (Defaulting to 1:1)
Manual scaling factor: 1.000000
Final scaling: 1 DXF unit = 1.0000 mm

Performance:
  - C++ import time: 0.4027 seconds
  - Total import time: 0.5834 seconds

Import settings:
  - Import hidden blocks: No
  - Import layout objects: No
  - Import points: Yes
  - Import texts and dimensions: No
  - Join geometry: No
  - Manual scaling factor: 1.000000
  - Use colors from the DXF file: Yes
  - Use layers: Yes

Entity counts:
  - BLOCK: 39
  - HATCH: 133 (*)
  - INSERT: 123
  - LWPOLYLINE: 152
  - MTEXT: 48
----------------------------
  Total entities read: 495
FreeCAD objects created: 303

System Blocks:
  - Other System Blocks: 3

(*) Entity type not supported by importer.

Unsupported features:
  - Entity type 'HATCH': 133 time(s). Examples: line 1558 (handle 9d), line 1690 (handle a1), line 1822 (handle a5), line 1954 (handle a9), line 5230 (handle aa), ...
--- End of summary ---

[dominik-warch]

Sorry, to add more context: The layers itself work fine when I export them from the corresponding layer. The combination/merge logic seems to be the problem.

[manisandro]

Yeah when DXF-exporting layers from multiple themes, the DXF files are merged client side, see [1]. The error about the duplicate block name could be a good hint where to start looking, probably these need to be unique-ified when merging the DXF trees.

[1] https://github.com/qgis/qwc2/blob/master/utils/DxfUtils.js