Bold Text Not Rendering Properly in Telegram Bot Messages with Python Telegram API

[hayart89]

I am building a Telegram bot using the python-telegram-bot library, and I am facing issues with rendering text formatting consistently in the bot's messages. I have tried multiple approaches, including MarkdownV2 and HTML for formatting, but the issue persists.

What I Tried:

1. MarkdownV2 Formatting
   Used parse_mode="MarkdownV2" to render formatted text.
   Example:

   await update.message.reply_text(
       "*This is formatted text*", 
       parse_mode="MarkdownV2"
   )

   Result: Formatted text failed to render in many cases, especially when the text included special characters. Escaping special characters didn't resolve the issue consistently.

2. HTML Formatting
   Used parse_mode="HTML" to render formatted text.
   Example:

   await update.message.reply_text(
       "<b>This is formatted text</b>", 
       parse_mode="HTML"
   )

   Result: Formatted text rendered correctly in some instances, but when special characters (like <, >, or &) were included in the text, the message either failed to send or rendered incorrectly.

3. Escaping Special Characters for MarkdownV2
   Attempted to escape characters like *, _, [, ], and others as per the Telegram documentation for MarkdownV2.
   Example:

   await update.message.reply_text(
       r"\*This is formatted text\*", 
       parse_mode="MarkdownV2"
   )

   Result: The message sent successfully, but formatting still failed to render in many cases.

4. Debugging Character Limits
   Ensured that messages did not exceed the Telegram character limit of 4096 characters.
   Result: Message length wasn't the issue; text formatting still failed intermittently.

Expected Behavior:

The formatted text should render consistently in messages sent by the bot, regardless of the presence of special characters.

Actual Behavior:

Text formatting fails to render consistently, and in some cases, the message fails entirely when special characters are present, even with escaping.

Environment Details:

• Python version: 3.9
• python-telegram-bot version: Latest (v20.x)
• Using MarkdownV2 and HTML as parse_mode

Steps to Reproduce:

1. Set up a simple Telegram bot using the python-telegram-bot library.
2. Send messages using MarkdownV2 or HTML with text formatting.
3. Include special characters (e.g., <, >, &) in the message.
4. Observe inconsistent rendering or message failure.

Questions:

• Is there a better approach to consistently render formatted text in Telegram bot messages?
• How can I handle special characters in MarkdownV2 or HTML without causing rendering issues?

What Didn’t Work:

• Escaping special characters for MarkdownV2.
• Switching to HTML for formatting.
• Simplifying messages to remove possible conflicts.

Looking forward to any advice or guidance!