mastra-ai/mastra · error · Error

Invalid ENV value for ${key}: multiline values are not suppo

Error message

Invalid ENV value for ${key}: multiline values are not supported.

What it means

FileEnvService.validateEnvEntry throws this when the VALUE for an env entry contains a carriage return or newline. .env files are line-based (KEY=VALUE per line), so multiline values would corrupt parsing of subsequent entries. The CLI rejects such values up front rather than writing a broken file.

Source

Thrown at packages/cli/src/services/service.env.ts:22

  abstract getEnvValue(key: string): Promise<string | null>;
  abstract setEnvValue(key: string, value: string): Promise<void>;
}

function escapeRegExp(value: string): string {
  return value.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
}

export class FileEnvService extends EnvService {
  private static readonly ENV_KEY_REGEX = /^[A-Za-z_][A-Za-z0-9_]*$/;

  private readonly filePath: string;

  private validateEnvEntry(key: string, value: string): void {
    if (!FileEnvService.ENV_KEY_REGEX.test(key)) {
      throw new Error(`Invalid ENV key: ${key}`);
    }
    if (/[\r\n]/.test(value)) {
      throw new Error(`Invalid ENV value for ${key}: multiline values are not supported.`);
    }
  }

  constructor(filePath: string) {
    super();
    this.filePath = filePath;
  }

  private envLineRegex(key: string, captureValue = false): RegExp {
    const pattern = captureValue ? `^${escapeRegExp(key)}=(.*)$` : `^${escapeRegExp(key)}=.*$`;
    return new RegExp(pattern, 'm');
  }

  private async updateEnvData({
    key,
    value,
    filePath = this.filePath,
    data,

View on GitHub (pinned to 75dd419e61)

Solutions

1. Replace newlines with an escape sequence, e.g. '\\n', and decode on read
2. Base64-encode multiline content: Buffer.from(value).toString('base64')
3. Strip whitespace: value.replace(/[\r\n]+/g, ' ') or .trim() if it is only trailing
4. Store multiline secrets in a file and pass a path in the env var instead

Example fix

// before
await service.updateEnvData({ PRIVATE_KEY: fs.readFileSync('key.pem', 'utf8') });
// after
await service.updateEnvData({ PRIVATE_KEY: Buffer.from(fs.readFileSync('key.pem', 'utf8')).toString('base64') });

function assertSingleLineEnvValue(key: string, value: string) {
  if (/\r|\n/.test(value)) throw new Error(`Env value for ${key} must not contain newlines`);
}
// or encode multiline content:
const encoded = /\r|\n/.test(value) ? Buffer.from(value).toString('base64') : value;

const isSingleLine = (value: string): boolean => !/[\r\n]/.test(value);

try {
  await service.updateEnvData(entries);
} catch (e) {
  if (e instanceof Error && e.message.startsWith('Invalid ENV value')) {
    console.error('Multiline env values are unsupported; base64-encode or flatten them.');
  } else throw e;
}

When it happens

Trigger: Calling updateEnvData with a value containing '\n' or '\r', e.g. multiline secrets (JSON blobs, private keys, certificates) pasted as-is, or values read from a multiline source.

Common situations: Storing a private key or JSON as an env var without encoding; copying a value from a terminal that included a trailing newline; generating values programmatically from multiline input.

Related errors

• Invalid ENV key: ${key}
• Invalid environment variable name: "${key}"
• ClaudeSDKAgent resumeData must include sessionId or continue
• CursorSDKAgent resumeData must include a message.
• CursorSDKAgent resumeData.agentId must be a string when prov

AI-assisted analysis of mastra-ai/mastra@75dd419e61 (2026-08-30). Data as JSON: /api/errors/f56ea9433507c6dc. Report an issue: GitHub.