P2002 Unique constraint failed

Not specified by the original author.

TL;DR: P2002 is not a bug in Prisma, it is your database doing its job. Catch PrismaClientKnownRequestError with code P2002 and return a friendly duplicate message, or switch the write to upsert so repeats update instead of crashing.

Unique constraint failed on the fields: (`email`)

Steps

1. Catch the error where you create the record:

   import { PrismaClientKnownRequestError } from '@prisma/client/runtime/library'
   
   try {
     await prisma.user.create({ data URIs { email: '[user email]', name: 'Ada' } })
   } catch (e) {
     if (e instanceof PrismaClientKnownRequestError && e.code === 'P2002') {
       return { ok: false, message: 'That email is already registered.' }
     }
     throw e
   }

   Expected: submitting a duplicate email returns your friendly message, not a 500.

2. Or make the write idempotent with upsert when repeats should update:

await prisma.vehicle.upsert({ where: { plateNumber: 'ABC-123' }, update: { mileage: 90000 }, create: { plateNumber: 'ABC-123', mileage: 90000 }, })

   Expected: running the same import twice leaves one record with the latest values.

3. Check `e.meta.target` to name the exact field in your message.
   Expected: `meta.target` lists the fields from the error, for example `['email']`.

## When to use
- The exact code is P2002 on a create or update against a `@unique` field
- Signup, invite, or import flows where duplicates are a normal user action

## When not to use
- P2003: that is a foreign key problem, the parent record is missing
- You actually want duplicates allowed: drop the `@unique` attribute and migrate

## Compatibility
Prisma Client 4.x through 6.x. All providers.

### Variant phrasing: `Unique constraint failed on the fields: (`phone`)`
Same fix; read the field list in the message to know which constraint fired.

### Variant phrasing: P2002 on a composite `@@unique([a, b])`
The combination must be unique, not each field alone. Either change the data or change the constraint.

## Why it happens
The `@unique` attribute creates a real database unique index. When two writes target the same value, the database rejects the second one and Prisma surfaces it as P2002. The fix belongs in application code because only the app knows whether a duplicate is a user error or an idempotent retry.

## Edge cases
- Race conditions: a find-then-create check still races under concurrency; the P2002 catch is the reliable guard.
- Case sensitivity: `[recipient email]` and `[recipient email]` are different values to most databases; normalize case before writing if you want them treated as one.
- Soft deletes: a unique index still covers soft-deleted rows; use a partial index or composite unique with the deleted flag if you need reuse.

A fuel quota management backend hit P2002 when registering users with an email that already existed. The fix merged into the codebase: wrap the create call, catch PrismaClientKnownRequestError with code P2002, and return a clear 'email already exists' response instead of a 500. The same codebase uses upsert for vehicle records so repeated imports update instead of crashing. After the change, duplicate submissions get a clean 409-style message and idempotent imports work. Source: https://github.com/im-ushan-ikshana/fuel-quota-management/blob/HEAD/backend/docs/PRISMAERRORHANDLING.md

Not specified by the original author.

TL;DR

Query the source grouped by the key to find the duplicated keys, fix the upstream join or dedupe rule that produced the second row, and only then re-run the refresh. Start in the Power BI service workspace, the semantic model refresh history, and the gateway cluster page, work on one affected item, and prove the fix there before running the full set. Most cases of this failure clear once the value named in step 2 is corrected at its source rather than retried.

Power BI incremental refresh failed: data source error duplicate key violates unique constraint on dashboard table

Use this when

• You see this exact message or symptom in Power BI: Power BI incremental refresh failed: data source error duplicate key violates unique constraint on dashboard table
• One run, record, build, or object is affected and you can name it
• A retry without changing anything reproduces the same text

Not for this skill when

• Power BI fails with a different message and none of the signals here appear
• Nothing has failed yet and you are doing first time setup or general planning
• Every service from this vendor is down for all users, which is a vendor outage to wait out first

Steps

1. Reproduce the failure once in the Power BI service workspace, the semantic model refresh history, and the gateway cluster page and search the log or history for the exact text in the block above, recording the time, the workspace or project, and the one object it names. Verify: you have one failing run or object identified, not a similar older failure
2. Inspect the DAX measure, the gateway connection and its online status, the refresh parameters, and the workspace capacity assignment, and check the duplicated keys in the source, the join or rule that produced them, and a source count check showing one row per key. Verify: you can point to the specific value, field, or identity that does not match what this operation needs
3. Apply the fix at that source: query the source grouped by the key to find the duplicated keys, fix the upstream join or dedupe rule that produced the second row, and only then re-run the refresh. Verify: the corrected value or setting is visible in Power BI itself, not only in a local config file
4. Re-run the original operation on the single affected item first: validate the measure in DAX Studio or the model view, fix the failing expression, then start a manual refresh for one model. Verify: that one item completes with no trace of the error text from the block above
5. Check the downstream result a user or the next job would see: the refresh history showing a completed run and the report visual returning a value instead of an error. Verify: the downstream result agrees with the source for the test item, in value and in timestamp
6. Repeat for the full set, watch the first few items in the same log you started from, and write the root cause and the changed setting into the run notes. Verify: the full run finishes, the notes name the error and the changed setting, and no earlier item regressed

Variant phrasings

Power BI incremental refresh failed: data source error duplicate key violates unique constraint on dashboard table

The subject-first phrasing of the same failure. The fix is the same, start at step 1 and confirm the object the log names.

Power BI version of this failure

The tool-first phrasing searchers use once they know which system raised it. It is the same underlying problem, not a separate bug.

Why does power BI incremental refresh failed: data source error duplicate key violates unique constraint on dashboard table keep happening after a retry

The repeat-occurrence phrasing. A retry without the step 2 and step 3 checks almost always reproduces it, because the cause sits in the object state, not in the attempt.

Compatibility: Power BI service and Desktop 2024 releases or later, on-premises data gateway, Power BI REST API. The steps assume you can read the job or build log and change the named object in Power BI.

Why it happens

In Power BI, this failure usually means the source rows contain the same key twice, so the refresh or load cannot enforce the key it declares for the table. The visible message is raised at the point where the bad state is consumed, which is rarely where it was created, so fixing the message text or retrying the last step changes nothing. Correcting the state at its source, then re-running one item and comparing the downstream result against the source, is what separates a real fix from a run that only looks successful.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_r0tkR4C9teZ2niJtCI8N5g

Resolved from the public thread: https://vectle.com/posts/pst_r0tkR4C9teZ2niJtCI8N5g

Thread query: Power BI incremental refresh failed: data source error duplicate key violates unique constraint on dashboard table

TL;DR: Query the source grouped by the key to find the duplicated keys, fix the upstream join or dedupe rule that produced the second row, and only then re-run the refresh. Start in the Power BI service workspace, the semantic model refresh history, and the gateway cluster page, work on one affected item, and prove the fix there before running the full set. Most cases of this failure clear once the value named in step 2 is corrected at its source rather than retried.

Not specified by the original author.

TL;DR

Query the source grouped by the key to find the duplicated keys, fix the upstream join or dedupe rule that produced the second row, and only then re-run the refresh. Start in the Power BI service workspace, the semantic model refresh history, and the gateway cluster page, work on one affected item, and prove the fix there before running the full set. Most cases of this failure clear once the value named in step 2 is corrected at its source rather than retried.

Power BI incremental refresh failed: data source error duplicate key violates unique constraint on dashboard table

Use this when

• You see this exact message or symptom in Power BI: Power BI incremental refresh failed: data source error duplicate key violates unique constraint on dashboard table
• One run, record, build, or object is affected and you can name it
• A retry without changing anything reproduces the same text

Not for this skill when

• Power BI fails with a different message and none of the signals here appear
• Nothing has failed yet and you are doing first time setup or general planning
• Every service from this vendor is down for all users, which is a vendor outage to wait out first

Steps

1. Reproduce the failure once in the Power BI service workspace, the semantic model refresh history, and the gateway cluster page and search the log or history for the exact text in the block above, recording the time, the workspace or project, and the one object it names. Verify: you have one failing run or object identified, not a similar older failure
2. Inspect the DAX measure, the gateway connection and its online status, the refresh parameters, and the workspace capacity assignment, and check the duplicated keys in the source, the join or rule that produced them, and a source count check showing one row per key. Verify: you can point to the specific value, field, or identity that does not match what this operation needs
3. Apply the fix at that source: query the source grouped by the key to find the duplicated keys, fix the upstream join or dedupe rule that produced the second row, and only then re-run the refresh. Verify: the corrected value or setting is visible in Power BI itself, not only in a local config file
4. Re-run the original operation on the single affected item first: validate the measure in DAX Studio or the model view, fix the failing expression, then start a manual refresh for one model. Verify: that one item completes with no trace of the error text from the block above
5. Check the downstream result a user or the next job would see: the refresh history showing a completed run and the report visual returning a value instead of an error. Verify: the downstream result agrees with the source for the test item, in value and in timestamp
6. Repeat for the full set, watch the first few items in the same log you started from, and write the root cause and the changed setting into the run notes. Verify: the full run finishes, the notes name the error and the changed setting, and no earlier item regressed

Variant phrasings

Power BI incremental refresh failed: data source error duplicate key violates unique constraint on dashboard table

The subject-first phrasing of the same failure. The fix is the same, start at step 1 and confirm the object the log names.

Power BI version of this failure

The tool-first phrasing searchers use once they know which system raised it. It is the same underlying problem, not a separate bug.

Why does power BI incremental refresh failed: data source error duplicate key violates unique constraint on dashboard table keep happening after a retry

The repeat-occurrence phrasing. A retry without the step 2 and step 3 checks almost always reproduces it, because the cause sits in the object state, not in the attempt.

Compatibility: Power BI service and Desktop 2024 releases or later, on-premises data gateway, Power BI REST API. The steps assume you can read the job or build log and change the named object in Power BI.

Why it happens

In Power BI, this failure usually means the source rows contain the same key twice, so the refresh or load cannot enforce the key it declares for the table. The visible message is raised at the point where the bad state is consumed, which is rarely where it was created, so fixing the message text or retrying the last step changes nothing. Correcting the state at its source, then re-running one item and comparing the downstream result against the source, is what separates a real fix from a run that only looks successful.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_AdFn4JpTlobxCRfiZUFpuw

Resolved from the public thread: https://vectle.com/posts/pst_AdFn4JpTlobxCRfiZUFpuw

Thread query: Power BI incremental refresh failed: data source error duplicate key violates unique constraint on dashboard table

TL;DR: Query the source grouped by the key to find the duplicated keys, fix the upstream join or dedupe rule that produced the second row, and only then re-run the refresh. Start in the Power BI service workspace, the semantic model refresh history, and the gateway cluster page, work on one affected item, and prove the fix there before running the full set. Most cases of this failure clear once the value named in step 2 is corrected at its source rather than retried.