An HTTP 400 Bad Request error indicates that the server cannot or will not process the request due to something perceived as a client error. When using Midjourney, this error typically occurs in one of three scenarios: you are using the Midjourney alpha web interface, you are interacting with Discord's slash command API, or you are running automation scripts through third-party Midjourney API wrappers.
Because Midjourney relies heavily on Discord's backend and its own web-app APIs, a 400 error means the data sent to the server is malformed, contains syntax errors, or uses unsupported parameters. Follow these practical troubleshooting steps to resolve the issue.
Step 1: Clean Web Browser Cookies and Cache
If you are using the Midjourney web interface (midjourney.com) to generate images, view your gallery, or manage your subscription, a 400 Bad Request is almost always caused by expired, corrupt, or conflicting browser cookies.
1. Open your browser settings and navigate to **Privacy and Security**.
2. Click on **Cookies and other site data** (or search for "cookies" in your browser's search bar).
3. Search for `midjourney.com` and select **Delete all shown**.
4. Clear your browser cache for the last 24 hours.
5. Restart your browser, navigate back to Midjourney, and log in again to force the creation of clean session tokens.
Step 2: Validate Prompt Parameters and Syntax
Incorrectly formatted prompts are a primary trigger for 400 errors when sending commands via Discord or API wrappers. Midjourney's parser will reject commands that do not strictly adhere to parameter syntax rules.
* **Check double dashes:** Ensure all parameters use two hyphens with no space between them (e.g., `--ar 16:9`, not `-ar 16:9` or `—ar 16:9` which often happens with mobile auto-correct).
* **Check parameter values:** Ensure you are using valid values. For example, `--version 6` or `--v 6` is valid, but `--v 7` or `--v 6.5` will fail.
* **Avoid conflicting parameters:** Do not combine incompatible parameters (e.g., using `--tile` with certain aspect ratios in older model versions).
* **Check for trailing spaces:** Ensure there are no double spaces or trailing punctuation marks directly attached to parameters.
Step 3: Check Image URLs in Image-to-Image Prompts
If your prompt contains image URLs for image prompts, character references (`--cref`), or style references (`--sref`), an invalid URL will throw an HTTP 400 error.
1. Verify that the URL points directly to an image file. It must end in `.png`, `.jpg`, `.jpeg`, or `.webp`.
2. Ensure the URL is publicly accessible. Direct links from Discord channels work, but links from private Google Drive folders, Dropbox, or authenticated web pages will be blocked.
3. Keep URLs clean. Remove tracking parameters (anything after the `?` in the URL) and test if the raw image loads in an incognito browser window first.
Step 4: Fix Payload Structure (For API & SDK Users)
If you are using a third-party developer API, an unofficial wrapper, or a Discord self-bot framework to trigger Midjourney, your JSON payload format may be incorrect.
* **Verify interaction types:** Discord requires application commands to have precise structural formats. Check that the payload containing your payload arguments (like application ID, guild ID, channel ID, and session ID) is populated correctly.
* **Sanitize payload strings:** Ensure prompt strings are properly escaped in your JSON code. Unescaped double quotes (`"`) or invalid control characters inside prompt payloads will break JSON parsing and return a 400 Bad Request.
* **Check body limits:** The payload must not exceed Discord's text field character limits (typically 2000 characters for prompts).
Step 5: Verify Channel Permissions and Bot Integrations
Sometimes, the Discord API returns a 400 Bad Request if the bot or the user account lacks the necessary permissions in the target channel.
1. Ensure the Midjourney Bot has **Send Messages**, **Use Slash Commands**, and **Embed Links** permissions in the channel you are using.
2. Try moving to a different channel or your direct messages (DMs) with the Midjourney Bot to see if the issue is channel-specific.
When to escalate
If you have cleared your browser cookies, verified your prompt syntax is flawless, and are still receiving HTTP 400 errors, the issue may be a temporary outage on Midjourney's side or a change in Discord's API schema.
* Check the **#status** channel in the official Midjourney Discord server for reports of widespread gateway errors.
* If you are using a third-party API wrapper, consult the wrapper developer's documentation, as Discord regularly updates its gateway specifications, requiring wrapper library updates.