File formats and size limits
Check channel media requirements before adding attachments to a flow.
Use a file type supported by the selected channel and the content control in Flow Builder. Channel API limits do not guarantee that Bual Pro accepts the same size or format. Follow a lower limit shown by the uploader or your account.
The channel requirements below were checked on 20 October 2026. Bual Pro's current upload limits and delivery behaviour have not been tested in a customer account.
Meta's supported media types specify:
| Media | Formats | Maximum size |
|---|---|---|
| Image | JPEG, PNG; 8-bit RGB or RGBA. | 5 MB |
| Audio | AAC, AMR, MP3, M4A, OGG with Opus. | 16 MB |
| Video | MP4 or 3GP; H.264 video with AAC audio, or no audio stream. | 16 MB |
| Document | TXT, PDF, DOC, DOCX, XLS, XLSX, PPT, PPTX. | 100 MB |
OGG audio must use the Opus codec and mono input. Video supports a single audio stream or none. An extension alone does not establish the codec or MIME type.
WhatsApp stickers have separate requirements; WebP is not listed as an ordinary image-message format. For template headers, also see WhatsApp template images.
Meta's Instagram message guide lists these media attachments for its linked-Page messaging integration:
| Media | Listed formats | Maximum size |
|---|---|---|
| Image | PNG, JPEG. | 8 MB |
| Audio | AAC, M4A, WAV, MP4. | 25 MB |
| Video | MP4, OGG, AVI, MOV, WEBM. | 25 MB |
| File | PDF. | 25 MB |
The upload guide also lists GIF images, while the message guide's image table lists PNG and JPEG. Confirm GIF support for your connection before relying on it. A channel API's PDF support does not establish that a PDF control is available in your Bual Pro account.
Messenger
Meta's asset guide supports image, audio, video, and file attachments. It lists a 25 MB asset limit, with a separate 8 MB maximum for images uploaded by URL. Other URL attachments have a 25 MB limit after encoding.
Use the correct media type and MIME type for the attachment. Meta also applies fetch timeouts to URL uploads. A file can fail even when its size is acceptable if the remote URL is inaccessible, too slow, or serves the wrong type.
Telegram
Telegram's Bot API distinguishes URL fetching from direct uploads:
| Sending method | Photos | Other files |
|---|---|---|
| Telegram fetches an HTTP URL. | Up to 5 MB. | Up to 20 MB. |
| New file uploaded with multipart form data. | Up to 10 MB. | Up to 50 MB. |
Its audio method uses MP3 or M4A for music-player audio. The video method uses MPEG-4 video; other formats can be handled as documents by Telegram. URL-based document sending is currently limited to PDF and ZIP.
These are Bot API requirements. Bual Pro's transfer method is unconfirmed, so do not assume its uploader accepts the larger direct-upload limits.
If a file is rejected
Check the actual format, MIME type, size, and codec where applicable. Renaming a file extension does not convert it. For a URL attachment, check that the recipient service can fetch the file and that the URL returns the intended media rather than a login page.
Preview the attachment in the selected channel before using it in a customer-facing flow. Record the error and the relevant file details if you need help investigating a failure.