Discord rejects hCaptcha token with 'invalid-response' — using CaptchaHandler

[lipkou]

I'm trying to handle Discord hCaptcha challenges using external CAPTCHA solving services (tested with SolveCaptcha and 2Captcha) via the CaptchaHandler class.

The services solve the CAPTCHA successfully, and I return the token as expected. However, Discord responds with: { "captcha_key": ["invalid-response"] }

I’m not sure what I’m doing wrong. Could someone please help me figure it out?

Code:

class CaptchaSolver(discord.CaptchaHandler):
    def solvecaptcha(self, data: dict, proxy: str, proxy_auth: aiohttp.BasicAuth) -> str:
        solver = Solvecaptcha(API_KEY)
        result = solver.hcaptcha(
            sitekey=data['captcha_sitekey'],
            data=data['captcha_rqdata'],
            url="https://discord.com/channels/@me",
        )
        return result['code']
    
    async def fetch_token(self, data: dict, proxy: str, proxy_auth: aiohttp.BasicAuth) -> str:
        loop = asyncio.get_running_loop()
        token = await loop.run_in_executor(None, self.solvecaptcha, data, proxy, proxy_auth)
        return token

bot = commands.Bot('>', self_bot=True, captcha_handler=CaptchaSolver())
bot.run("MyToken")

Details:
discord.py-self version: 2.0.1
CAPTCHA triggers when I try to send the first DM to a user (a bot, in my case)