A build fails — checklist

When a build turns failed, the cause is almost always in the build logs (split by step). Here are the most useful checks.

1. Read the logs

Open the build → logs, and spot the step that fails (fetching the code, building the image…). The error message there is explicit.

Symptom in the logs	Likely cause	Fix
`Dockerfile not found`	wrong Dockerfile path or wrong source folder	fix the Dockerfile path / the source folder (monorepo) in the build configuration
Dependency installation fails	missing dependency or incompatible version	fix the dependency file in your repository
Branch / commit not found	the branch given does not exist	check the branch when starting the build
Access denied to the repository	expired or revoked token	reconnect the repository (see Connecting a repository)
Unsuitable strategy	Buildpacks does not detect the language, or a Dockerfile is expected	choose the right strategy (Dockerfile vs Buildpacks)

Strategy: Dockerfile if you provide a Dockerfile; Buildpacks otherwise.
Source folder: for a monorepo, point at the right subfolder (e.g. services/api).
Dockerfile path: relative to the source folder.
Build variables: present if your build needs them.

After fixing things (in the repository or in the configuration), restart the build. Follow the logs again.