Fix HTTP 404 Errors When Downloading Business Central AL Symbols
Question details
The user needs to resolve an HTTP 404 Not Found error that occurs when trying to download AL symbols for Microsoft Dynamics 365 Business Central.
- Product
- Microsoft Dynamics 365 Business Central
- Device & OS
- Windows
- Scenario
- Setting up a development environment in Visual Studio Code and attempting to download AL language symbols from the Business Central server.
- Observed behavior
- The system returns an HTTP 404 error, indicating that the development metadata or web endpoint configured in launch.json is incorrect, unreachable, or the service is not running.
Ensure that you have administrative access to the Business Central Server instance and that your Windows Firewall is temporarily configured to allow troubleshooting on the developer port.
Verify and Update launch.json Configuration
Use this solution to correct mismatches in your server credentials, instance name, or port numbers that cause the 404 endpoint error.
The HTTP 404 error most commonly occurs when Visual Studio Code cannot locate the specific endpoint on the server due to incorrect values in the launch.json configuration file. Validating these parameters ensures VS Code targets the correct active service.
Run Windows PowerShell as an Administrator to retrieve your current Business Central server configuration.
Execute the Get-NAVServerConfiguration cmdlet for your specific server instance to confirm the exact DeveloperServicesPort being used.
Open the launch.json file in your Visual Studio Code project. Update the "server", "serverInstance", and "port" fields to exactly match the values verified in PowerShell.
Open the Command Palette in Visual Studio Code (Ctrl+Shift+P) and select 'AL: Download Symbols' to retry the download process.
Enable the Developer Service Endpoint
Use this method if your launch.json is correct but the Business Central server is actively refusing or ignoring developer connections.
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Frequently Asked Questions
How can I check if my Business Central service instance is actually running?
You can open the Windows Services app (services.msc) and look for the 'Microsoft Dynamics 365 Business Central Server' service. Ensure its status is listed as 'Running'.
Why does my AL: Download Symbols command fail immediately without prompting for credentials?
This usually indicates that the server URL constructed from your launch.json is entirely unreachable. Double-check that your server address and port are correct, and that no firewall is blocking outbound traffic from VS Code.
What is the default Developer Services port for Business Central?
By default, the Developer Services port is set to 7049, but this can be altered by system administrators during installation. Always verify the port using the Administration tool or PowerShell.
Does my Windows Firewall block Business Central developer ports by default?
Yes, unless explicitly allowed during installation, Windows Firewall blocks incoming connections on custom ports. You must create an Inbound Rule allowing TCP traffic on your specific developer port (e.g., 7049).
