What causes "Missing Browserless API Token" in FlowiseAI/Flowise?

Create a Browserless credential in the credential manager and paste the API token from the Browserless dashboard.

FlowiseAI/Flowise · error · Error

Missing Browserless API Token

Error message

Missing Browserless API Token

What it means

Thrown by BrowserlessMCP.getTools when getCredentialParam('browserlessApiToken', ...) returns falsy. Browserless is a hosted MCP server (https://mcp.browserless.io/mcp) that requires a Bearer token; without it the toolkit would connect and immediately 401. The guard fails fast at tool-registration time so the agent never receives a broken tool set.

Source

Thrown at packages/components/nodes/tools/MCP/Browserless/BrowserlessMCP.ts:91

        const _mcpActions = nodeData.inputs?.mcpActions
        let mcpActions = []
        if (_mcpActions) {
            try {
                mcpActions = typeof _mcpActions === 'string' ? JSON.parse(_mcpActions) : _mcpActions
            } catch (error) {
                console.error('Error parsing mcp actions:', error)
            }
        }

        return tools.filter((tool: any) => mcpActions.includes(tool.name))
    }

    async getTools(nodeData: INodeData, options: ICommonObject): Promise<Tool[]> {
        const credentialData = await getCredentialData(nodeData.credential ?? '', options)
        const apiToken = getCredentialParam('browserlessApiToken', credentialData, nodeData)

        if (!apiToken) {
            throw new Error('Missing Browserless API Token')
        }

        const serverParams = {
            url: 'https://mcp.browserless.io/mcp',
            headers: {
                Authorization: `Bearer ${apiToken}`
            }
        }

        const toolkit = new MCPToolkit(serverParams, 'sse')
        await toolkit.initialize()

        const tools = toolkit.tools ?? []

        return tools
    }
}

View on GitHub (pinned to abe4a8601a)

Solutions

Create a Browserless credential in the credential manager and paste the API token from the Browserless dashboard.
Select that credential on the Browserless MCP node.
Verify the token is non-empty and free of surrounding whitespace.
If the account lapsed, regenerate a token in the Browserless dashboard and update the credential.

Example fix

// before — node.credential points to a generic HTTP credential without browserlessApiToken
// after — create a Browserless credential with browserlessApiToken set, then bind it on the node

Defensive patterns

Strategy: validation

Validate before calling

function assertBrowserlessToken(cred: { browserlessApiToken?: string }) {
  if (!cred.browserlessApiToken?.trim()) throw new Error('Create a Browserless credential with a non-empty browserlessApiToken')
}

Type guard

function hasBrowserlessToken(c: unknown): c is { browserlessApiToken: string } {
  return !!c && typeof (c as any).browserlessApiToken === 'string' && (c as any).browserlessApiToken.trim().length > 0
}

Prevention

Create the Browserless credential before adding the node.
Bind the credential on the node dropdown.
Regenerate the token in the Browserless dashboard if the account lapsed.
Trim whitespace when pasting the token.

When it happens

Trigger: The node has no credential attached, an attached credential of the wrong type, or a Browserless credential with an empty token field. Also when the credential was deleted but the node still references it.

Common situations: First-time setup where the user added the node but not the credential; expired trial / cancelled Browserless account where the token was cleared; selecting a different credential type in the dropdown.

Related errors

AI-assisted analysis of FlowiseAI/Flowise@abe4a8601a (2026-08-12). Data as JSON: /api/errors/19288bc4ceec924c. Report an issue: GitHub.