Telegram bot throws bad request error when sending image via URL

[Finn_Mystery]

I am working on a Telegram bot and trying to send an image to users using a web URL. However, I keep getting an error message that says the file identifier or URL is incorrect.

Here’s the code I’m using:

await telegramBot.SendPhotoAsync(chatMessage.Chat.Id, "https://192.168.1.100/" + "welcome" + ".jpg");

When I run this code, I get the following error:

Bad Request: Wrong file identifier/HTTP URL specified

What could be causing this issue and how can I fix it? Any help would be appreciated.

[charlottew]

Telegram’s servers are unable to access private IP addresses such as 192.168.1.100, which is the reason for the error you are encountering. The URL is not publicly accessible. In my experience, you have a few alternatives: you can host the image on a public server or utilize cloud storage solutions like AWS S3. If you prefer to send directly from your local environment, you can use the InputFile method to stream the image rather than providing a URL.

[Claire29]

yeah, it’s definetly the issue! telegram can’t hit local addresses. try uploading the image to a server with a public URL, or use ngrok for a temp public tunnel to your local server.

[sofiap]

I encountered a similar issue while developing a Telegram bot. The root cause is that 192.168.1.100 is a private IP address, only accessible within your local network. Consequently, Telegram cannot access the image via that URL. I recommend using the InputFile class instead of a public URL. This allows you to send the image directly from your local files by reading them as a stream. Here’s a sample implementation:

using (var fileStream = new FileStream(@"C:\path\to\welcome.jpg", FileMode.Open, FileAccess.Read))
{
    await telegramBot.SendPhotoAsync(chatMessage.Chat.Id, new InputFile(fileStream, "welcome.jpg"));
}

This method eliminates the need for public URLs and effectively transmits local files.

[jade_journey]

The Problem:

You’re trying to send images to Telegram users using a web URL, but you’re receiving a “Bad Request: Wrong file identifier/HTTP URL specified” error. Your code attempts to use a local IP address (192.168.1.100) to access the image, which is inaccessible to the Telegram servers.

Understanding the “Why” (The Root Cause):

The Telegram Bot API operates over the public internet. It cannot access resources located on private networks using private IP addresses like 192.168.1.100. These addresses are only reachable from within your local network. Therefore, the Telegram servers cannot retrieve the image from the specified URL, resulting in the error.

Step-by-Step Guide:

Step 1: Host the Image Publicly. The simplest solution is to upload your image to a publicly accessible server (e.g., using cloud storage like AWS S3, Google Cloud Storage, or a simple hosting service). Once uploaded, replace the local URL in your code with the new, public URL.

Step 2: Update Your Code. Replace the local IP address URL with the public URL of your image. Your updated code will look like this:

string publicImageUrl = "https://your-public-storage-bucket.com/welcome.jpg"; // Replace with your public image URL
await telegramBot.SendPhotoAsync(chatMessage.Chat.Id, publicImageUrl);

Step 3 (Alternative): Use InputFile (if direct local access is critical). If for some reason you absolutely cannot host the image publicly and require sending the image directly from your local machine, you can use the InputFile class to stream the image. This is generally less efficient than using a public URL, and it should be avoided if possible. Here’s how you would modify your code:

using (var fileStream = new FileStream(@"C:\path\to\welcome.jpg", FileMode.Open, FileAccess.Read)) //Replace with your absolute path
{
    await telegramBot.SendPhotoAsync(chatMessage.Chat.Id, new InputFile(fileStream, "welcome.jpg"));
}

Step 4: Verify the Path. Double-check the file path in the InputFile method. Using an incorrect or inaccessible path will result in the image not being sent. Use absolute paths to avoid ambiguity.

Common Pitfalls & What to Check Next:

• Incorrect File Path: Ensure the path to your image file (@"C:\path\to\welcome.jpg") is absolutely correct. Double-check spelling and capitalization.
• File Permissions: Verify that your application has the necessary read permissions for the specified image file.
• Image Format: Ensure the image file is in a supported format (JPEG, PNG, GIF).
• File Size: Telegram has size limits for files. If the image is too large, it will fail to send.
• Public URL Accessibility: If using a public URL, ensure the URL is correctly configured and the image is publicly accessible. Check for any firewall rules preventing external access.

Still running into issues? Share your (sanitized) config files, the exact command you ran, and any other relevant details. The community is here to help!