User Sync relies on a user’s universal identifier to uniquely identify each user in Firstup. Because this identifier is foundational to how users are tracked, it cannot be changed automatically through User Sync.

If the identifier in your upload does not match the identifier already stored in Firstup, the file will fail with an error.

What the Error Means

You may see an error message similar to:

“Cannot assign additional identifiers to email users.”

This error indicates that the universal identifier in the User Sync file does not match the universal identifier currently associated with that user’s email address in Firstup.

Because User Sync uses the universal identifier to uniquely identify users, it cannot overwrite or replace that value during processing.

Why This Happens

This error typically occurs when:

• A user’s universal identifier was changed in the source system

• The identifier stored in Firstup was set incorrectly during initial setup

• Multiple identifiers have been associated with the same email address over time

How to Resolve the Error

Step 1: Identify the Correct Universal Identifier

First, determine which value is correct:

• If the value in Firstup is correct, update the source for your User Sync file to match it.

• If the value in the User Sync file is correct, the Firstup record must be updated manually as follows.

Step 2: Update the Universal Identifier

For Individual Users

If only a small number of users are affected:

1. Open Studio

2. Locate the user

3. Edit the user profile

4. Replace the universal identifier with the correct value

5. Save the changes

Once the user’s email address and universal identifier in Firstup match the uploaded file, the error will be resolved.

For Multiple Users

If many users have incorrect universal identifiers:

• Bulk updates can be made using the User Management API, if your organization has access to this tool

• If you do not have API access, your Customer Success Manager can coordinate a bulk update as a service with Firstup

After the identifiers are corrected in bulk, subsequent User Sync uploads will process successfully.

Step 3: Re-upload the User Sync File

Once all affected users’ identifiers match:

• Re-upload the User Sync file

• The error will no longer occur

Important Notes

• Universal identifiers cannot be updated through SFTP User Sync

• Manual or bulk updates must be completed before reprocessing

• Email address and universal identifier values must match exactly

Key Takeaways

• This error is caused by mismatched universal identifiers

• User Sync cannot overwrite an existing identifier

• Single-user fixes can be done in Studio

• Bulk fixes can be handled via API or through your CSM

• Once values are aligned, uploads will succeed