VS Code mssql extension throws “Error Loading. Refresh to try again” when expanding External File Formats for Fabric Data Warehouse and Fabric SQL Analytics Endpoint

Type: Bug

# Issue Summary

When connected to a Fabric Data Warehouse or Fabric SQL Analytics Endpoint, expanding the External File Formats node under External Resources causes an exception. The UI displays the message:

“Error Loading. Refresh to try again”

Refreshing does not resolve the issue, and the error occurs consistently.

# Steps to Reproduce

Open VS Code.

Connect to a Microsoft Fabric Data Warehouse or Fabric SQL Analytics Endpoint using Entra ID authentication.

In the SQL Server explorer:

Expand the database

Expand External Resources

Expand External File Formats

Observe the error message.

# Expected Result

One of the following:

The External File Formats node is hidden or disabled for Fabric endpoints where the feature is unsupported, or

The node expands successfully but shows no objects

# Actual Result

Expanding External File Formats throws an exception.

The UI displays:
“Error Loading. Refresh to try again”

Refreshing does not resolve the issue.

No actionable or descriptive error message is provided.

Extension version: 1.38.0
VS Code version: Code 1.108.1 (585eba7c0c34fd6b30faac7c62a42050bfbc0086, 2026-01-14T14:55:44.241Z)
OS version: Windows_NT x64 10.0.19045
Modes:

System Info

|Item|Value|
|---|---|
|CPUs|Intel(R) Core(TM) i7-1065G7 CPU @ 1.30GHz (8 x 1498)|
|GPU Status|2d_canvas: enabled
direct_rendering_display_compositor: disabled_off_ok
gpu_compositing: enabled
multiple_raster_threads: enabled_on
opengl: enabled_on
rasterization: enabled
raw_draw: disabled_off_ok
skia_graphite: disabled_off
trees_in_viz: disabled_off
video_decode: enabled
video_encode: enabled
webgl: enabled
webgl2: enabled
webgpu: enabled
webnn: disabled_off|
|Load (avg)|undefined|
|Memory (System)|31.60GB (10.10GB free)|
|Process Argv|--crash-reporter-id 04d2b347-f107-489c-a662-44c1faca28d3|
|Screen Reader|no|
|VM|0%|

A/B Experiments

```
vsliv368:30146709
binariesv615:30325510
nativeloc1:31344060
dwcopilot:31170013
dwoutputs:31242946
copilot_t_ci:31333650
e5gg6876:31282496
pythonrdcb7:31342333
6518g693:31436602
aj953862:31281341
63221493:31336333
cloudbuttont:31379625
3efgi100_wstrepl:31403338
use-responses-api:31390855
defaultusage:31403421
je187915:31401257
ec5jj548:31422691
cmp-ext-treat:31426748
cp_cls_t_966_ss:31446430
c0683394:31419495
ge8j1254_inline_auto_hint_haiku:31431912
nes-autoexp-10:31446583
a5gib710:31434435
5j92g670_sonnet:31440727
rename_enabled:31436409
7a04d226_do_not_restore_last_panel_session:31438103
anthropic_thinking_t:31432745
406hc587_ask_agent:31428393
preserve_tokens:31444547
cp_cls_t_1081:31443828
copilot-nes-oct-trt:31432596
ia-use-proxy-models-svc:31450090
nes-jump-on-with-edit-1122:31442054
nes-slash-models-on:31441832
nes-set-to-on:31441941
a43f0576c:31442824
ts_provider_disabled:31446105
c0ci8992_validated:31449878
nes-conv-2-2:31447849

```

Start by reproducing the issue in the SQL Server explorer with a Fabric Data Warehouse or Fabric SQL Analytics Endpoint using Entra ID authentication, then trace the External Resources and External File Formats loading path. Done means the unsupported node is hidden or disabled, or it expands without an exception and displays no objects; the current error should no longer appear.

Written by the indexing model from the issue text.