# Ajv-error not compatible with 3.7

**URL:** <https://jsonforms.discourse.group/t/ajv-error-not-compatible-with-3-7/2807>\
**Category:** General\
**Created:** [March 11, 2026, 7:30pm UTC](https://jsonforms.discourse.group/t/ajv-error-not-compatible-with-3-7/2807 "2026-03-11T19:30:51Z")\
**Posts on this page:** 7\
**Page:** 1

<div class="post-metadata">

**Author:** ![clysss](https://yyz2.discourse-cdn.com/free1/user_avatar/jsonforms.discourse.group/clysss/32/996_2.png) [@clysss](https://jsonforms.discourse.group/u/clysss)\
**Post date:** [March 11, 2026, 7:30pm UTC](https://jsonforms.discourse.group/t/ajv-error-not-compatible-with-3-7/2807/1 "2026-03-11T19:30:51Z")

</div>

I’m using customs ajv-errors.

after update from 3.6 to 3.7 the error messages are no more customs…

my main call looks like ;  
\<JsonForms

```
        //i18n={{translate: translator}}

        schema={schemasQuery.data.schema as JsonSchema}

        uischema={schemasQuery.data.uiSchema}

        data={isEmpty(jsonFormData) ? schemasQuery.data.data : jsonFormData}

        renderers={renderers}

        cells={materialCells}

        ajv={xcreateAjv()}

        validationMode="ValidateAndShow"

        onChange={({ data, errors }) => {

          setJsonFormData(data);

          setJsonFormErrors(errors);

        }}

```

and my ajv.ts containng the xcreateajv is :

import ajvErrors from ‘ajv-errors’;

import { createAjv } from ‘@jsonforms/core’;

const formats = {

email: {

```
type: 'string', 

validate: (data: string) => /^\[^\\s@\]+@\[^\\s@\]+\\.\[^\\s@\]+$/.test(data),

```

},

phone: {

```
type: 'string',

validate: (data: string) => /^\\+\[0-9\]+$/.test(data), 

```

},

url: {

```
type: 'string',

validate: (data: string) => /^https:\\/\\/.+/.test(data),

```

},

linkedin: {

```
type: 'string', 

validate: (data: string) => /^https:\\/\\/(www\\.)?linkedin\\.com\\/(in|company)\\/\[\\w-\]+\\/?$/.test(data),

```

},

// reconnaître le format SVG et arrêter les messages d’erreur //////////////////////DO NOT WORK as not in schema (in schemaui)

‘upload-logo’: {

```
validate: (str: string) => {

  return typeof str === 'string';

},

errorMessageKey: 'validation_svgInvalid',

errorMessage: "URL invalid - must begin with https://",

```

}

};

export const xcreateAjv = () =\> {

const myAjv=createAjv({

```
allErrors: true,

verbose: true,

$data: true, 

strict: false,

messages: true

```

});

ajvErrors(myAjv);

// Define the totalPercentage keyword

myAjv.addKeyword({

```
keyword: 'totalPercentage',

type: 'array',

validate: function (schema: any, data: any) {

  if (!Array.isArray(data)) return false; // Ensure data is an array

  const total = data.reduce((sum: number, entry: any) => sum + (entry.percent || 0), 0);

  return total === 100; // Check if total equals 100

},

errors: false, // Set to true if you want to use custom error messages

```

});

```
Object.entries(formats).forEach((\[name, format\]) => {

  myAjv.addFormat(name, format.validate);

});

```

return myAjv;

};

I tried with or without updating ajv package, both failed

which version of ajv should we use?

how should we write with new jsonforms?

Thx a lot!

---

<div class="post-metadata">

**Author:** ![lucas-koehler](https://yyz2.discourse-cdn.com/free1/user_avatar/jsonforms.discourse.group/lucas-koehler/32/336_2.png) [@lucas-koehler](https://jsonforms.discourse.group/u/lucas-koehler)\
**Post date:** [March 16, 2026, 4:25pm UTC](https://jsonforms.discourse.group/t/ajv-error-not-compatible-with-3-7/2807/2 "2026-03-16T16:25:00Z")

</div>

Hi @clysss , there should not have been an AJV update between 3.6 and 3.7 or at least not a major version one.  
Effectively, 3.7.0 uses AJV `8.13.0`.  
Pre-release version `3.7.0-alpha.0` uses `8.18.0`. This is recommended to be used as AJV belo 8.18 has a severe security flaw.

Can you give a whole example to execute and specify which version of ajv errors you use.  
It could be worth checking if you updated the ajv errros version with updating to JSON Forms 3.7. Maybe that leads to unexpected behavior.

Best regards,  
Lucas

---

<div class="post-metadata">

**Author:** ![clysss](https://yyz2.discourse-cdn.com/free1/user_avatar/jsonforms.discourse.group/clysss/32/996_2.png) [@clysss](https://jsonforms.discourse.group/u/clysss)\
**Post date:** [March 16, 2026, 4:42pm UTC](https://jsonforms.discourse.group/t/ajv-error-not-compatible-with-3-7/2807/3 "2026-03-16T16:42:15Z")

</div>

Hello Lucas  
,thanks a lot for your message,  
Can I send you the files by email?.. including the package.json  
Best regards

---

<div class="post-metadata">

**Author:** ![lucas-koehler](https://yyz2.discourse-cdn.com/free1/user_avatar/jsonforms.discourse.group/lucas-koehler/32/336_2.png) [@lucas-koehler](https://jsonforms.discourse.group/u/lucas-koehler)\
**Post date:** [March 16, 2026, 5:43pm UTC](https://jsonforms.discourse.group/t/ajv-error-not-compatible-with-3-7/2807/4 "2026-03-16T17:43:08Z")

</div>

Hi @clysss ,  
sure you can. Note that I will post the solution here though and will mention essential facts (e.g. an installed package version).  
If you can, pushing them to a small repo might be even better 🙂  
Best regards,  
Lucas

---

<div class="post-metadata">

**Author:** ![clysss](https://yyz2.discourse-cdn.com/free1/user_avatar/jsonforms.discourse.group/clysss/32/996_2.png) [@clysss](https://jsonforms.discourse.group/u/clysss)\
**Post date:** [March 16, 2026, 6:04pm UTC](https://jsonforms.discourse.group/t/ajv-error-not-compatible-with-3-7/2807/5 "2026-03-16T18:04:18Z")

</div>

Sure, i’ll be happy you put the reply here:)

---

<div class="post-metadata">

**Author:** ![lucas-koehler](https://yyz2.discourse-cdn.com/free1/user_avatar/jsonforms.discourse.group/lucas-koehler/32/336_2.png) [@lucas-koehler](https://jsonforms.discourse.group/u/lucas-koehler)\
**Post date:** [March 26, 2026, 12:38pm UTC](https://jsonforms.discourse.group/t/ajv-error-not-compatible-with-3-7/2807/6 "2026-03-26T12:38:01Z")

</div>

Hi @clysss ,

To summarize the issue to help others that might run into the same issue:

You’re using `@jsonforms/core` together with `ajv-errors` and getting a massive type error like this on the `ajvErrors(myAjv)` call:

```auto
Argument of type 'Ajv' is not assignable to parameter of type 'Ajv'.
  Types of property 'opts' are incompatible.
    ...
      Property '_names' is protected but type 'Scope' is not a class derived from 'Scope'.

```

The root cause is that **`@jsonforms/core` bundles its own nested copy of `ajv`** inside `node_modules/@jsonforms/core/node_modules/ajv/`. When you call `createAjv()` from `@jsonforms/core`, it returns an `Ajv` instance typed against that internal copy. But `ajv-errors` (installed at the top level) expects an `Ajv` instance typed against the top-level `ajv`. TypeScript sees these as two entirely different and incompatible types, even though they are the same library.

## Fix: force deduplication with `resolutions` when using yarn

In your `package.json`, add a `resolutions` field to tell your package manager to use a single version of `ajv` everywhere:

```json
"resolutions": {
  "ajv": "^8.18.0"
}

```

After re-installing dependencies, this replaces `@jsonforms/core`’s nested `ajv` copy with the top-level one, making both `createAjv()` and `ajv-errors` share the same type space.

For me, the error is gone with that.

Hope that helps,  
Lucas

---

<div class="post-metadata">

**Author:** ![clysss](https://yyz2.discourse-cdn.com/free1/user_avatar/jsonforms.discourse.group/clysss/32/996_2.png) [@clysss](https://jsonforms.discourse.group/u/clysss)\
**Post date:** [April 24, 2026, 6:57pm UTC](https://jsonforms.discourse.group/t/ajv-error-not-compatible-with-3-7/2807/7 "2026-04-24T18:57:09Z")

</div>

> [@lucas-koehler](#):
>
> ```auto
> "resolutions": {
> "ajv": "^8.18.0"
> }
> 
> ```

Thanks a lot, seems to work now 🙂