---
bc-version: [all]
domain: mcp
keywords: [businesscentral, mcp, bc-mcp-bridge, company, header, display-name, config, troubleshooting]
technologies: [al, mcp]
countries: [w1]
application-area: [all]
---

# BC MCP `Company` Header Must Be the Exact `Navn` Field, Not `Vist navn`

## Description

`~/.bc-mcp.config.json`'s `company` value is sent as the literal `Company`
HTTP header to the BC MCP endpoint. It must exactly match the company's
**`Navn`** field in Business Central's company list — not the **`Vist navn`**
(display name) field. The two are often different strings for the same
company, and BC's own company picker UI shows the display name more
prominently, making it the natural (wrong) one to copy.

## Incident (2026-07-31)

CURABIS's own `businesscentral` MCP server failed after "working all
evening" with a generic client-side "connection timed out after 30000ms" —
no useful error surfaced to the developer. Root cause: `company` was set to
`"CURABIS ApS"` (the `Vist navn`), while BC's actual `Navn` field is
`"Curabis ApS"`. BC's own API rejected the mismatched header with a fast,
clear 400 error — but `bc-mcp-bridge.js` had a separate bug
(`bc-mcp-bridge-must-surface-non-2xx-responses-before-sse-parsing`, same
incident) that swallowed the error body, turning a sub-200ms server error
into a 30-second client-side hang with no diagnostic.

## Verification

If `businesscentral` MCP fails, check BC's company list page (Virksomheder /
Companies) and compare the `Navn` column — not `Vist navn` — against
`~/.bc-mcp.config.json`'s `company` value, character for character. Do not
assume the value that "looks right" from the picker UI is the one the API
needs.

## Anti-Pattern

    // WRONG: copied from BC's company switcher, which shows Vist navn
    { "company": "CURABIS ApS" }

## Compliant

    // CORRECT: copied from the Navn column on the company list page
    { "company": "Curabis ApS" }

## Scope

Every machine with `~/.bc-mcp.config.json` configured — this is a
machine-local file, not something Mode B can fix centrally. The template
(`bc-mcp.config.template.json`) carries an explicit warning about this
distinction as of 2026-07-31, but a machine already onboarded before that
date needs its existing file checked manually.

## Follow-up (2026-08-03) — a correct header does not guarantee the request resolves

The `Internal_CompanyNotFound` symptom recurred on 2026-08-03 on two
independent developer machines, both with `company` already set to the
correct `Navn` value (`"Curabis ApS"`) per this rule. The header-mismatch
cause above was confirmed absent both times — yet the error still occurred,
intermittently, within the same working day. Restarting Claude Code (which
respawns the `bc-mcp-bridge.js` process and re-establishes the MCP session)
was observed to restore working state, though this has not been root-caused.

This means a correct `Navn`-matching header is **necessary but not proven
sufficient**: the same-looking error can have a second, distinct cause tied
to the long-running bridge/session rather than a static config value. A
developer who has already verified the header matches `Navn` character for
character should not keep re-checking that same field. Next steps, in order:

1. Restart Claude Code once and retry.
2. If it recurs, check BC-side state that a config file can't reveal: the
   Entra app registration's (`BC_DevelopmentMCP`) company-permission
   assignment, and whether the relevant MCP Server Configuration
   (`Model Context Protocol (MCP) Server Configurations`, BC page 8351) is
   still Active.
3. If it recurs across restarts and BC-side checks pass, treat it as a
   SaaS-side incident and escalate to Microsoft support rather than
   re-diagnosing the client config a third time.

Root cause of the session/restart-correlated failure mode is still open —
this section records the observed correlation, not a confirmed mechanism.