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Vishesh Duggar

5x founder. Co-founder & CTO Product @vamstar. 15+ years building and advising startups of all sizes. If you're building something cool, I'd love to hear about it.

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I recently faced an intriguing issue while integrating NextAuth with MySQL using Prisma – an issue related to column lengths.

The Error

The trouble began with this error during runtime:

prisma:error Invalid `prisma.account.create()` invocation:

The provided value for the column is too long for the column’s type. Column: for [next-auth][error][adapter_error_linkAccount] Invalid prisma.account.create() invocation:

The provided value for the column is too long for the column’s type. Column: for </code>

This error was a clear indication that the data NextAuth tried to store in one of the Account model’s columns exceeded the maximum length defined in the Prisma schema for MySQL.

Understanding the Cause

In Prisma, when using MySQL, a string field without a specified length defaults to VARCHAR(191). This default is often sufficient for most use cases. However, with OAuth tokens, such as those managed by NextAuth, the data length can significantly exceed this limit.

The Solution

The solution was to explicitly define the maximum length for each token-related string field in the Account model. This was crucial as the tokens provided by OAuth providers, like Google, can be quite lengthy.

Here’s the updated portion of the schema.prisma:

model Account { // ... other fields ...

access_token String? @db.VarChar(512) refresh_token String? @db.VarChar(1024) id_token String? @db.VarChar(2048)

// … other fields and model configurations … } </code>

By specifying @db.VarChar(&lt;length&gt;) for each field, we tell Prisma to prepare the MySQL database columns with the appropriate lengths. This ensures that the tokens returned by OAuth providers fit comfortably in the database without being truncated.

Applying the Changes

After updating the schema, it’s essential to create and apply a new migration. This can be done using the command:

npx prisma migrate dev --name adjust_token_lengths

This command generates a new migration file reflecting these changes and applies it to the local development database.

Key Takeaways

  • Always Check Field Lengths: When integrating third-party services, always consider the data they return and how it fits into your database schema.
  • Prisma and MySQL: Prisma’s default string length might not always suit your needs, especially with external data like OAuth tokens.
  • Migration is Crucial: Schema changes require creating and applying a new migration to ensure that your database structure is up-to-date.


Integrating NextAuth with Prisma for a MySQL database can present unique challenges, particularly regarding data length in token fields. By understanding the nature of the data being stored and appropriately adjusting the Prisma schema, we can ensure smooth integration and avoid runtime errors related to data truncation.

Remember, adapting to these challenges is part of what makes software development both a continuous learning experience and a field ripe with problem-solving opportunities.

15+ Years strategising and delivering growth, engineering, customer value and more. I have served as a CTO to multiple organizations, including Vamstar, AtruHelp, Billaway, SuperSehat, and more.

If you're a founder or CEO eager to move faster and seek tailored strategies for your unique challenges, don't navigate this journey alone. Reach out to me. Together, we can dissect, refine, and optimize your enterprise's trajectory to withstand the tests of time and innovation. Let's make your vision not just a goal, but an impending reality.

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