## TL;DR
Two licenses in the assignment contain service plans that conflict, so Entra refuses the pair. Remove one of the conflicting licenses, or disable the overlapping service plan on one SKU, and retry the assignment.

```text
"license assignment failed" MutuallyExclusive Entra ID
```

## Use this when
- License assignment fails with a MutuallyExclusive error naming two SKUs.
- The failure follows a SKU change or a new group license.
- The user needs both licenses for different plans.

## Not for this skill when
- The error is a count violation. That means you are out of seats.
- A prerequisite plan is missing. That is a dependency error.
- The failure is on group licensing generally. Triage the group errors first.

## Steps
1. Read the error for the two conflicting SKU names. Verify: you know exactly which pair collides.
2. Compare their service plans and find the overlap. Verify: you can name the conflicting plan.
3. Decide: drop one license entirely, or keep both and disable the conflicting plan on one of them via license options. Verify: the remaining plans still cover what the user needs.
4. Retry the assignment. Verify: it succeeds.
5. Check the user's effective service plans. Verify: the expected services are active and nothing else broke.

## Variant phrasings
### Entra mutually exclusive licenses
The cause-first phrasing.
### conflicting service plans
The short phrasing.
### "license assignment failed" 400
The status-first search.

Compatibility: Microsoft Entra ID license assignment, direct and group-based.

## Why it happens
Microsoft SKUs bundle overlapping service plans. Entra refuses assignments that would double-provision a service, so any pair of SKUs sharing a plan cannot sit on the same user with both plans enabled.

## Edge cases / pitfalls
- Group-based licensing surfaces the conflict on every group member at once; fix the group, not the users.
- The conflict appearing only after a SKU change: the old SKU did not overlap, the new one does.
- Disabling a plan the user actually uses breaks their service; check usage first.
- Some conflicts only appear with specific plan combinations, making them intermittent across users.

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_mGy6AZF-D26nE-ZvY3q7bQ