Telegram Bot API · error code

Telegram error 400: Bad Request: wrong remote file identifier specified

Permanent - do not retryHTTP 400400 Bad Request: files and media

Last verified against Telegram Bot API reference

What Telegram returns
Bad Request: wrong remote file identifier specified: <detail varies>

What error 400 means

The string you passed looks like a Telegram file_id but Telegram cannot decode or accept it. The description carries a trailing detail that varies, such as Wrong character in the string, can't unserialize it. Wrong last symbol, or Wrong padding in the string. Treat the prefix as stable and the tail as diagnostic.

File IDs are opaque, base64-like tokens that encode the file reference and an access hash. They are tied to the bot that received them: an ID obtained by one bot cannot be used by another. They also carry type information, so a photo file_id passed to sendDocument can fail. And the Bot API FAQ notes that file_id strings may change over time even though file_unique_id stays constant, so very old stored IDs may stop working.

The request, chat and token are fine; the identifier is not.

What it looks like

{"ok":false,"error_code":400,"description":"Bad Request: wrong remote file identifier specified: Wrong character in the string"}

Why it happens

  • The file_id was truncated, URL-decoded twice, or had characters altered by a form or spreadsheet.
  • The ID came from a different bot token.
  • A photo file_id was used with sendDocument (or another type mismatch); Telegram may also report type of file mismatch.
  • An old ID that is no longer valid for this bot.

How to fix Telegram error 400

  1. 1Compare the stored ID with the one in the original update, character by character.
  2. 2Confirm the ID was produced by the same bot that is now sending.
  3. 3Use the send method matching the original media type, or copyMessage to avoid the issue.
  4. 4If the ID is old, re-upload the file and store the new file_id.

How to stop it recurring

Store file_ids in a text column without transformation, alongside the bot ID that obtained them and the media type. For long-lived assets, keep the original file in your own storage so you can re-upload when an ID is rejected. Use file_unique_id for matching, never for sending.

Libraries pass this through as a generic 400 with the description intact, so log it verbatim; the trailing detail ('Wrong character in the string', 'Wrong padding') identifies the corruption. Sibling failures: wrong file identifier/HTTP URL specified for values that are not even the right shape, and file is too big once the reference resolves but the size rules bite (see file limits).

Official reference: Telegram Bot API reference. See all Telegram error codes or the Telegram limits and quotas.

Related codes

Error 400 - quick answers

What does Telegram error 400 mean?

The string you passed looks like a Telegram file_id but Telegram cannot decode or accept it. The description carries a trailing detail that varies, such as Wrong character in the string , can't unserialize it. Wrong last symbol , or Wrong padding in the string . Treat the prefix as stable and the tail as diagnostic. File IDs are opaque, base64-like tokens that encode the file reference and an access hash.

How do I fix Telegram error 400?

1. Compare the stored ID with the one in the original update, character by character. 2. Confirm the ID was produced by the same bot that is now sending. 3. Use the send method matching the original media type, or copyMessage to avoid the issue. 4. If the ID is old, re-upload the file and store the new file_id.

Should I retry after error 400?

No. Retrying the same request produces the same error; the condition has to be fixed first. Treat it as a permanent failure for that message and surface it, rather than looping.

Stop debugging Telegram by hand

Connect the channel through Conferbot: tokens, webhooks and retries are handled, failures show as readable status.