500 Error at /1/oauth2/authorize_submit After User Clicks "Allow" in OAuth Flow

We’re encountering a persistent OAuth issue that affects only one user on a Dropbox Business account.

Issue Summary:

• Affected user: Dropbox Business (Standard or Advanced)
• OAuth scopes requested:
  files.content.write files.content.read files.metadata.read files.metadata.write account_info.read
• These are individual scopes only—no team scopes are requested.
• The app is private and not listed in the App Center.

What Happens:

• The user successfully reaches the Dropbox OAuth consent screen.
• After clicking "Allow", Dropbox returns a 500 Internal Server Error at this URL:
  https://dropbox.com/1/oauth2/authorize_submit
• The error occurs after consent, and Dropbox never redirects back to our app.

What We’ve Established:

• OAuth works for individual Dropbox users.
• OAuth works for other Dropbox Business users, including admins and non-admins.
• App permissions in the Admin Console for "Other Apps" being set to "Block" does not appear to be the issue.
• No use of team-level scopes.
• The affected user removed and reauthorized the app.
• We replicated the flow in Dropbox Advanced with other team users and couldn’t reproduce the issue.

Request for Help:
We’d appreciate any insights into:

• Why a 500 error might occur at /1/oauth2/authorize_submit for one user only.
• Whether this could be related to team configuration or a Dropbox-side authorization issue.
• Any Dropbox-side logs or tools that could help investigate this issue.

We’re happy to provide HAR files, timestamps, or other technical details.

Thanks in advance!