Render pre-deploy runs on a separate instance: no disk, no filesystem carryover

TL;DR

It's fine for database migrations and CDN uploads, but don't use it to generate files the app needs at runtime (put that in the build command instead). Putting Render migrations in the pre-deploy command?

Fix

1. It's fine for database migrations and CDN uploads, but don't use it to generate files the app needs at runtime (put that in the build command instead). Expected: You get the expected result; the problem is gone.

When to use

• You are setting up or using this Render pre-deploy runs on a separate instance feature.
• The symptom matches: no disk, no filesystem carryover.

When NOT to use

• Unrelated Render pre-deploy runs on a separate instance issues (different feature, different failure).
• You need general documentation for the tool; check the official docs instead.

Compatibility

Reported against Render pre-deploy runs on a separate instance.

Variant phrasings

no disk, no filesystem carryover

Why it happens

Official docs (Deploying on Render): documents that the pre-deploy command runs after the build but before the deploy, and is meant for migrations or asset uploads. The gotcha agents hit: the pre-deploy command executes on a SEPARATE instance from the running service. Changes you make to the filesystem are not reflected in the deployed service, and you do not get access to the service's attached persistent disk. It also consumes pipeline minutes and is only available on paid web services, private services, and background workers.

Edge cases

• If your error message differs even slightly, this is probably a different issue; search the exact text.
• If the fix does not help, capture the full error output and check the source link for updates.

Source: Official docs (Deploying on Render): documents that the pre-deploy command runs after the build but before the deploy, and is meant for migrations or asset uploads. The gotcha agents hit: the pre-deploy command executes on a SEPARATE instance from the running service. Changes you make to the filesystem are not reflected in the deployed service, and you do not get access to the service's attached persistent disk. It also consumes pipeline minutes and is only available on paid web services, private services, and background workers.

Verified resolution: Putting Render migrations in the pre-deploy command? Know its limits: it runs on a separate instance, so anything it writes to the local filesystem vanishes and it can't touch your persistent disk. It's fine for database migrations and CDN uploads, but don't use it to generate files the app needs at runtime (put that in the build command instead). If a deploy's migrations silently did nothing, this isolation is usually why. Note the pre-deploy step consumes pipeline minutes like the build does, and it isn't available on free web services.

Source URL: https://docs.render.com/deploys