Troubleshooting & FAQ Leave feedback

Solutions to the most common GroupDocs.Assembly MCP server issues — server not appearing in the client, startup failures, missing native dependencies, and first-launch timeouts.

Note

Platform-specific troubleshooting: runtime problems depend on which build you run. For the dnx runner, native graphics libraries, and the Docker channel, see Troubleshooting (.NET). The issues on this page apply to every platform.

1. Restart the client — every client reads its MCP config only at startup.
2. Check the config file location for your OS (per-client reference) and that the entry sits under the right root key (mcpServers for Claude Desktop/Cursor/Windsurf, servers for VS Code/VS 2022).
3. Validate the JSON — a trailing comma silently breaks the whole file. If you used the installer, a timestamped .bak of your previous config sits next to the file for comparison.

A cold cache: on the very first use the server’s package or image is still downloading while the client is already waiting on the connection. Warming it once fixes it for good — the exact command depends on your build: .NET.

These are properties of the build you run rather than of MCP, so the fixes live with the platform:

Pass the template’s and the data file’s names inside the storage folder — contract-template.docx, repo/data/release-4.2.0.json — not full paths from your machine. When a name is not found the tool answers with the files it can see, so the agent can correct itself; check that list against GROUPDOCS_MCP_STORAGE_PATH.

Because its placeholders are not Assembly tags. {{name}}, ${name} and [[name]] are other engines’ syntax and stay in the document as text; Assembly reads <<[name]>>. get_template_fields reports “The template contains 2 ‘{{…}}’ placeholder(s). GroupDocs.Assembly does not process that syntax and leaves it as text; write «[name]» instead.”

The template reads a field the data does not have — names are case-sensitive. The error names the field and the fix, for example “The template reads ‘Email’, which the data does not have.” Add the field, or pass allowMissingMembers: true to print nothing for it. Details: inspect and fix a template.

A date-only JSON string such as "2026-11-12" is read as a date and shifted by the machine’s UTC offset. Write "2026-11-12T00:00:00" and format it in the template — <<[contract.Date]:"d MMMM yyyy">>. The Docker image runs in UTC and is not affected.

No. The model writes data — a JSON object — and the template decides the layout, the wording around the values, the tables and the charts. That is the point: the document looks the same every time, and a reviewer can check the data instead of re-reading prose.

Yes — <<image>> and <<doc>> tags load whatever path or URL their expression returns. Treat templates as trusted input, like code, and run the server with one mounted folder — see on-premise deployment.

Yes. Templates built for the GroupDocs.Assembly library work unchanged; the server feeds them JSON, XML, CSV or table data instead of .NET objects. Templates that reach .NET types or methods not available on plain data may need a small rewrite.

Ask your agent “list your GroupDocs assembly tools and the license status” — it should name get_template_fields, assemble_document, assemble_per_record, get_document_info, get_supported_formats, get_license_status. For a scripted check that performs the real MCP handshake and a live call through the engine, see verifying a .NET installation.

Post your config (redact license paths) and the client name in the Assembly forum — we answer MCP questions daily. Bugs: GitHub issues.