Unable to resolve dependency tree when updating to Nodemailer V7

[stanlee786]

Environment

System:
OS: Linux 6.16 Arch Linux
CPU: (12) x64 AMD Ryzen 5 7640U w/ Radeon 760M Graphics
Memory: 8.82 GB / 14.93 GB
Container: Yes
Shell: 4.0.2 - /usr/bin/fish
Binaries:
Node: 22.18.0 - ~/.local/share/nvm/v22.18.0/bin/node
npm: 11.5.2 - ~/.local/share/nvm/v22.18.0/bin/npm
npmPackages:
next: ^15.5 => 15.5.0
next-auth: ^4.24 => 4.24.11
react: ^19.1 => 19.1.1

Reproduction URL

https://github.com/stanlee786/next-auth-example

Describe the issue

When trying to update from Nodemailer V6 to V7, I get the following error:

npm warn ERESOLVE overriding peer dependency
npm error code ERESOLVE
npm error ERESOLVE could not resolve
npm error
npm error While resolving: next-auth@5.0.0-beta.29
npm error Found: nodemailer@7.0.5
npm error node_modules/nodemailer
npm error   peerOptional nodemailer@"^6.8.0" from @auth/core@0.40.0
npm error   node_modules/next-auth/node_modules/@auth/core
npm error     @auth/core@"0.40.0" from next-auth@5.0.0-beta.29
npm error     node_modules/next-auth
npm error       next-auth@"beta" from the root project
npm error
npm error Could not resolve dependency:
npm error peerOptional nodemailer@"^6.6.5" from next-auth@5.0.0-beta.29
npm error node_modules/next-auth
npm error   next-auth@"beta" from the root project
npm error
npm error Conflicting peer dependency: nodemailer@6.10.1
npm error node_modules/nodemailer
npm error   peerOptional nodemailer@"^6.6.5" from next-auth@5.0.0-beta.29
npm error   node_modules/next-auth
npm error     next-auth@"beta" from the root project
npm error
npm error Fix the upstream dependency conflict, or retry
npm error this command with --force or --legacy-peer-deps
npm error to accept an incorrect (and potentially broken) dependency resolution.

Nodemailer V7 contains the following breaking change:

• SESv2 SDK support, removed older SES SDK v2 and v3 , removed SES rate limiting and idling features

How to reproduce

Try updating Nodemailer V6 to V7 in a Next.js 15 environment configured with NextAuth. Alternatively you can try installing Nodemailer V7, this will have the same result.

Expected behavior

Latest NextAuth version to support Nodemailer V7 and update without error.

[sshuvoo]

I don't think there should be a peer dependency between Nodemailer and NextAuth, since they serve completely different purposes.
As a workaround, you can install Nodemailer with:

npm install nodemailer --force

If it works without breaking your setup, you can continue with it.

Ideally though, this needs to be fixed upstream by updating NextAuth’s peer dependency range to allow Nodemailer v7.

[19leva89]

Agreed, I have the same incompatibility error when upgrading Nodemailer V6 to V7.

[stanlee786]

I don't think there should be a peer dependency between Nodemailer and NextAuth, since they serve completely different purposes. As a workaround, you can install Nodemailer with:

npm install nodemailer --force

If it works without breaking your setup, you can continue with it.

Ideally though, this needs to be fixed upstream by updating NextAuth’s peer dependency range to allow Nodemailer v7.

@sshuvoo This works, but is not ideal. As you said NextAuth's peer dependency range should be updated to allow Nodemailer V7.