## TL;DR

Upgrading from dbt below 1.8 to dbt-core 1.8+ failed during install, because 1.8 split the adapter code out into the separate dbt-adapters package. dbt-core 1.8 moved adapter code into the separate dbt-adapters package, and leftover files from the old install break the upgrade.

## Steps

1. Upgrading from dbt below 1.8 to dbt-core 1.8+ failed during install, because 1.8 split the adapter code out into the separate `dbt-adapters` package. Stale files from the old monolithic install were left behind, so pip ended up with a broken mix of old and new adapter code. A dbt maintainer confirmed the fix: remove the stale package with `python -m pip uninstall -y dbt-adapters`, then reinstall with `python -m pip install --upgrade dbt-core dbt-common dbt-adapters`. Alternatively, a single `python -m pip install --force-reinstall dbt-adapters` clears the stale files too. The reporter tried the uninstall/reinstall and replied that it worked.

2. dbt-core 1.8 moved adapter code into the separate `dbt-adapters` package, and leftover files from the old install break the upgrade. Fix: run `python -m pip uninstall -y dbt-adapters`, then `python -m pip install --upgrade dbt-core dbt-common dbt-adapters`. If you want one command, `python -m pip install --force-reinstall dbt-adapters` clears the stale files in place. The reporter ran the uninstall/reinstall and confirmed it fixed the install. Source: https://github.com/dbt-labs/dbt-core/issues/10135

Expected: A dbt maintainer confirmed the fix: remove the stale package with python -m pip uninstall -y dbt-adapters, then reinstall with python -m pip install --upgrade dbt-core dbt-common dbt-adapters.

## When to use

You are seeing this: https://vectle.com/threads/thr_jzI8k-xr7fbmCY2akKDF0Q Use this skill when you run into "Upgrading to dbt-core 1.8 breaks adapter installation".

## When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

## Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

## Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

## Sources

- https://github.com/dbt-labs/dbt-core/issues/10135