BAML internal error (AWSBedrock): video file should have bee

Error message

BAML internal error (AWSBedrock): video file should have been resolved to base64

What it means

The Bedrock video path (Nova models) also requires media content pre-resolved to base64 or URL. Encountering BamlMediaContent::File at this point means the resolution pass skipped the video, so BAML treats it as an unrecoverable internal inconsistency and bails.

Source

Thrown at engine/baml-runtime/src/internal/llm_client/primitive/aws/aws_client.rs:1233

                        ))
                    }
                }
            }
            BamlMediaType::Video => {
                let format = bedrock::types::VideoFormat::from(
                    {
                        let mime_type = media.mime_type_as_ok()?;
                        match mime_type.strip_prefix("video/") {
                            Some(s) => s.to_string(),
                            None => mime_type,
                        }
                    }
                    .as_str(),
                );
                // AWS Bedrock supports video for Nova models with specific format
                match &media.content {
                    BamlMediaContent::File(_) => {
                        anyhow::bail!(
                            "BAML internal error (AWSBedrock): video file should have been resolved to base64"
                        )
                    }
                    BamlMediaContent::Url(url) => Ok(bedrock::types::ContentBlock::Video(
                        bedrock::types::VideoBlock::builder()
                            .set_format(Some(format))
                            .set_source(Some(bedrock::types::VideoSource::S3Location(
                                bedrock::types::S3Location::builder()
                                    .set_uri(Some(url.url.clone()))
                                    .build()
                                    .context("Failed to build S3Location block")?,
                            )))
                            .build()
                            .context("Failed to build Video document block")?,
                    )),
                    BamlMediaContent::Base64(b64_media) => Ok(bedrock::types::ContentBlock::Video(
                        bedrock::types::VideoBlock::builder()
                            .set_format(Some(format))

View on GitHub (pinned to bd85ce9dee)

Solutions

Upgrade BAML to the latest version.
Pass the video as a URL or base64 data rather than a raw file path.
Ensure mime_type/video format is set so the resolver handles the file correctly.
File a bug with baml-lang/baml including the exact media definition.

Example fix

// before
video baml_video({ url: "file://./clip.mp4" })
// after
video baml_video({ url: "data:video/mp4;base64,<base64-data>" })

Defensive patterns

Strategy: validation

Validate before calling

if (video.url?.startsWith('file://')) { video.url = 'data:video/mp4;base64,' + fs.readFileSync(video.url.slice(7)).toString('base64'); }

Type guard

const isResolvedVideo = (m) => typeof m.url === 'string' && (m.url.startsWith('data:video/') || m.url.startsWith('http'));

Try / catch

try { await b.VideoPrompt(video) } catch (e) { if (String(e).includes('video file should have been resolved')) { /* inline base64 / upgrade BAML */ } else throw e; }

Prevention

Use URLs or base64 data for video sent to Bedrock Nova models.
Set the video mime_type/format explicitly.
Keep the BAML runtime up to date.

When it happens

Trigger: Sending video media to an AWS Bedrock Nova model where the media content is still a File variant (unresolved local file reference) when to_media_message builds the ContentBlock.

Common situations: Using video inputs with Bedrock Nova models in a BAML build where file:// video references are not resolved, or hand-constructed media objects that bypass resolution.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/6af41a7ec94a9a0e. Report an issue: GitHub.