If an image, video, audio file or PDF will not send, check the per-channel format and size limits, your storage space and the private-reply restriction.
You want to send a price list as a PDF and get told this file type cannot be sent on this channel; or a product video bounces back as too large. Instagram and WhatsApp accept different formats and different sizes, and the panel applies those rules before sending so you are not left with Meta's cryptic error text. This guide lists the limits and the fixes.
⚠️ Note: These limits are Meta's and apply to every tool using their API. If you can send a file from the phone app but not from the panel, this is why; the API's accepted list is narrower.
You may be seeing one of these situations:
A message saying this file type cannot be sent on this channel.
A message saying the file is too large.
A message saying storage is full.
The file was sent but never reached the person.
A concrete example: an architecture practice wants to send a project image over WhatsApp and is told the file is too large. The same file goes through fine on Instagram. The cause is that the limits differ: images are capped at 5 MB on WhatsApp and 8 MB on Instagram. Re-exporting as JPEG at 3 MB lets it through on both.
If you build a flow that runs on both channels, always prepare files against the tighter limit; otherwise the flow works on one channel and quietly fails on the other.
Format and size limits per channel
A file must match the channel's list on both format and size. Even a correct type is refused if the format is not on the list.
Instagram
Image — JPEG or PNG, up to 8 MB.
Video — MP4, up to 25 MB.
Audio — MP4 audio, up to 25 MB. MP3 is not accepted on Instagram.
Document — PDF, up to 25 MB.
WhatsApp
Image — JPEG or PNG, up to 5 MB.
Video — MP4, up to 16 MB.
Audio — MP3, OGG or MP4 audio, up to 16 MB.
Document — PDF, up to 95 MB.
The attachment button in the composer only opens the types that channel accepts, so picking the wrong type is already hard.
Bring the file inside the limits
Shrink the image. Photos taken on a phone are often over 8 MB. Export as JPEG at a lower resolution.
Re-encode the video. Use MP4 / H.264, drop the resolution to 1080p and lower the bitrate.
Convert HEIC and WebP files. Those formats are not accepted; export as JPEG or PNG.
Compress the PDF. On scanned documents, lowering the resolution shrinks the file noticeably.
Use the media library. Images uploaded to Media are compressed and converted to the format the channels require, so sending from there is the safest route.
If storage is full
The media library has a space limit per plan.
Open Media and look at the Storage used box, shown as used out of the limit.
If you are told storage is full, you need to free space.
Delete files you no longer use. Before deleting, use the By automation filter to see which flow uses which file.
The portfolio owner can upgrade the plan for more space.
If you are told you can create at most a certain number of folders, reduce them; deleting a folder keeps the files inside and moves them out of any folder.
If the file was sent but never arrived
Check the message status. If it says it could not be sent, read the reason underneath.
"File not found; upload it again." The source file was deleted from the library.
"The file could not be read." The file is corrupt, or its contents do not match its extension.
If the connection has dropped, sends are refused; check the connection status.
Files do not travel in a private reply to a comment
This is the restriction that surprises people most in automations.
A message sent as a private reply to a comment carries plain text only.
If the message step in your flow has a file, buttons, a card or list rows, those are dropped. The run log records what was dropped.
The log also shows the reason saying files cannot be sent in a private reply to a comment.
The fix: make the first message plain text, and send the file in a second message after the person replies and the window opens.
Other known issues and limits
Incoming files are not stored. Meta forbids storing media people send; a file is read only at the moment it is needed. An attachment from an older message may no longer open.
Uploading media depends on your role. The Viewer role cannot upload; an Agent can upload but not delete.
Publishing limits are separate. Files uploaded to Instagram as posts follow different rules; see my post was not published.
Message text has its own limit. A message being too long for the channel is not about the file.
The media section may be closed for your role. If Media is missing from the menu, ask for the access policy to be checked.
If you have followed every step and the problem continues, contact our Support team.