FlowiseAI/Flowise · error · Error

Invalid JSON in the ChatOpenAI's BaseOptions: ${exception}

Error message

Invalid JSON in the ChatOpenAI's BaseOptions: ${exception}

What it means

ChatOpenAICustom is a thin sibling of ChatOpenAI and reproduces the same BaseOptions JSON-parse guard. When the BaseOptions string fails JSON.parse, the SyntaxError is re-thrown with the ChatOpenAI's-label message. (Note: the label says 'ChatOpenAI' even though this node is ChatOpenAICustom — a copy-paste artifact, but the failure mode is identical.)

Source

Thrown at packages/components/nodes/chatmodels/ChatOpenAICustom/ChatOpenAICustom.ts:160

            openAIApiKey,
            apiKey: openAIApiKey,
            streaming: streaming ?? true
        }

        if (maxTokens) obj.maxTokens = parseInt(maxTokens, 10)
        if (topP) obj.topP = parseFloat(topP)
        if (frequencyPenalty) obj.frequencyPenalty = parseFloat(frequencyPenalty)
        if (presencePenalty) obj.presencePenalty = parseFloat(presencePenalty)
        if (timeout) obj.timeout = parseInt(timeout, 10)
        if (cache) obj.cache = cache

        let parsedBaseOptions: any | undefined = undefined

        if (baseOptions) {
            try {
                parsedBaseOptions = typeof baseOptions === 'object' ? baseOptions : JSON.parse(baseOptions)
            } catch (exception) {
                throw new Error("Invalid JSON in the ChatOpenAI's BaseOptions: " + exception)
            }
        }

        if (basePath) await checkDenyList(basePath)

        if (basePath || parsedBaseOptions) {
            obj.configuration = {
                baseURL: basePath,
                defaultHeaders: parsedBaseOptions
            }
        }

        const model = new ChatOpenAI(obj)
        return model
    }
}

module.exports = { nodeClass: ChatOpenAICustom_ChatModels }

View on GitHub (pinned to abe4a8601a)

Solutions

JSON-lint the BaseOptions string and save the corrected version.
If the message says 'ChatOpenAI' but you are on ChatOpenAICustom, remember the label is shared — fix BaseOptions on the ChatOpenAICustom node specifically.
Pass an object rather than a string when constructing programmatically to bypass parsing.
Start from a minimal valid object and add headers one at a time.

Example fix

// before
{ "X-Key": 'abc', } // mixed quotes + trailing comma -> throws [93]

// after
{ "X-Key": "abc" }

Defensive patterns

Strategy: validation

Validate before calling

function parseBaseOptions(raw) {
  if (!raw) return undefined
  if (typeof raw === 'object') return raw
  try { return JSON.parse(raw) }
  catch (e) { throw new Error(`ChatOpenAICustom BaseOptions JSON invalid: ${e.message}`) }
}
const parsedBaseOptions = parseBaseOptions(nodeData.inputs?.baseOptions)

Type guard

function isHeadersObject(v: unknown): v is Record<string, string> {
  if (typeof v !== 'object' || v === null || Array.isArray(v)) return false
  return Object.values(v).every(x => typeof x === 'string')
}

Try / catch

try {
  return await initChatOpenAICustom(nodeData, options)
} catch (e) {
  // Note: error label says 'ChatOpenAI' even on the Custom node
  if (e.message.includes("Invalid JSON in the ChatOpenAI's BaseOptions")) {
    throw new Error('Fix BaseOptions JSON on the ChatOpenAICustom node (label is shared with ChatOpenAI).')
  }
  throw e
}

Prevention

Remember the error label is shared — fix BaseOptions on whichever node you are actually using.
JSON-lint the value before saving.
Use object inputs when constructing programmatically.
Add a UI-side validator to catch this before save.

When it happens

Trigger: The ChatOpenAICustom node's BaseOptions field holds malformed JSON; same parser failures as [92]. Reachable only when baseOptions is a truthy string.

Common situations: Users pointing at a custom OpenAI-compatible endpoint paste a headers object with JSON syntax errors; confusion between the ChatOpenAI and ChatOpenAICustom nodes leads to fixing the wrong node; docs example copied with formatting artifacts.

Understand the failure class

Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

AI-assisted analysis of FlowiseAI/Flowise@abe4a8601a (2026-08-12). Data as JSON: /api/errors/4fe2656f5d833f4f. Report an issue: GitHub.