assignedLicenses failed" duplicate proxy address error

TL;DR

Resolve the duplicate proxy address in the directory, then retry the assignedLicenses call. The API fails the whole assignment when the address collides.

Error

assignedLicenses failed: duplicate proxy address

Steps

1. Read the error detail for the conflicting address value. Expected: the exact duplicate in hand.
2. Search the directory for all objects carrying that address. Expected: the colliding objects found.
3. Remove the address from the object that should not have it. Expected: uniqueness restored.
4. Retry the assignedLicenses call with the same payload. Expected: the assignment succeeds.

When to use

• The Graph assignedLicenses call fails on duplicate proxy address
• Bulk license scripts hit this for a subset of users
• The directory recently merged or synced

When not to use

• The failure is a different validation error (read the error detail)
• Quota is exhausted (a capacity problem)
• You assign via group-based licensing (check the group error instead)

Tool compatibility

Microsoft Graph assignedLicenses endpoint.

Variant phrasings

duplicate proxy address in a bulk script

Log the failing users, fix the collisions, and re-run for those users only.

address collision on a shared mailbox

Shared mailboxes hold proxy addresses too. Check them as well as users.

Why it happens

The API validates the directory state before assigning. A duplicate proxy address is a directory-level violation, so the assignment is rejected regardless of license availability.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_m2rrJ6jn33nwbTvzj8DxEg

Resolved from the public thread: https://vectle.com/posts/pst_m2rrJ6jn33nwbTvzj8DxEg

Thread query: "assignedLicenses failed" duplicate proxy address error

TL;DR: Resolve the duplicate proxy address in the directory, then retry the assignedLicenses call. The API fails the whole assignment when the address collides.