# Error on LDAP user federation - Test authentication on version v16.1.1

**URL:** <https://forum.keycloak.org/t/error-on-ldap-user-federation-test-authentication-on-version-v16-1-1/13435>\
**Category:** Configuring the server\
**Tags:** user-federation\
**Created:** [February 4, 2022, 2:18pm UTC](https://forum.keycloak.org/t/error-on-ldap-user-federation-test-authentication-on-version-v16-1-1/13435 "2022-02-04T14:18:34Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![rvukovic](https://avatars.discourse-cdn.com/v4/letter/r/e56c9b/32.png) [@rvukovic](https://forum.keycloak.org/u/rvukovic)\
**Post date:** [February 4, 2022, 2:18pm UTC](https://forum.keycloak.org/t/error-on-ldap-user-federation-test-authentication-on-version-v16-1-1/13435/1 "2022-02-04T14:18:34Z")

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Hi,

System:  
Windows/Linux  
Java 8

Keycloak v15 is working ok but when I try the new version of Keycloak 16.1.1 I was not able to use LDAP user-federation (AD).  
Authentication is not possible anymore and I am receiving the next error:

```auto
ERROR [org.keycloak.services.error.KeycloakErrorHandler] (default task-3) Uncaught server error: java.lang.NoSuchMethodError: java.nio.ByteBuffer.clear()Ljava/nio/ByteBuffer;
        at org.keycloak.vault.DefaultVaultRawSecret.close(DefaultVaultRawSecret.java:90)
        at org.keycloak.vault.DefaultVaultTranscriber.getCharSecret(DefaultVaultTranscriber.java:84)
        at org.keycloak.storage.ldap.idm.store.ldap.LDAPContextManager.getVaultSecret(LDAPContextManager.java:108)
        at org.keycloak.storage.ldap.idm.store.ldap.LDAPContextManager.createLdapContext(LDAPContextManager.java:72)
        at org.keycloak.storage.ldap.idm.store.ldap.LDAPContextManager.getLdapContext(LDAPContextManager.java:100)
        at org.keycloak.services.managers.LDAPServerCapabilitiesManager.testLDAP(LDAPServerCapabilitiesManager.java:99)
        at org.keycloak.services.resources.admin.RealmAdminResource.testLDAPConnection(RealmAdminResource.java:958)

```

Java 8 JRE or Java 11 JRE???: [Server Installation and Configuration Guide](https://www.keycloak.org/docs/latest/server_installation/#recommended-additional-external-documentation)  
And here it is stated that java 11 is required: [Keycloak - Getting started - OpenJDK](https://www.keycloak.org/getting-started/getting-started-zip)

This is error is clearly a compatibility problem…

---

<div class="post-metadata">

**Author:** ![sighanse](https://yyz2.discourse-cdn.com/free1/user_avatar/forum.keycloak.org/sighanse/32/3709_2.png) [@sighanse](https://forum.keycloak.org/u/sighanse)\
**Post date:** [February 10, 2022, 5:47pm UTC](https://forum.keycloak.org/t/error-on-ldap-user-federation-test-authentication-on-version-v16-1-1/13435/2 "2022-02-10T17:47:13Z")

</div>

I had to temporary upgrade to OpenJDK11. Hope they resolve this problem.

> <https://github.com/keycloak/keycloak/issues/9320>
>
> \### Describe the bug
> 
> I have an LDAP configuration with Active Directory which w…orks well with keycloak 14 and Java 8.
> 
> I tested the same LDAP configuration with keycloak 16.1.0 and I had the following error when I made a request to \*\*test the authentication\*\* of the LDAP configuration. 
> !\[ldap\](https://user-images.githubusercontent.com/39064501/147194073-95cfec0e-94ee-4409-aa22-520ceeaed229.png)
> !\[ldap-keycloak\](https://user-images.githubusercontent.com/39064501/147194084-8ac27a5c-84ac-4318-9ba5-b08847e5972f.png)
> 
> \*\*Upon upgrading to Java 11, the issue was resolved.\*\*
> 
> 
> \### Version
> 
> 16.1.0
> 
> \### Expected behavior
> 
> Based on the installation prerequisites: \[https://www.keycloak.org/docs/latest/server\_installation/#:~:text=Java%208%20JRE%20or%20Java%2011%20JRE\](https://www.keycloak.org/docs/latest/server\_installation/#:~:text=Java%208%20JRE%20or%20Java%2011%20JRE), keycloak 16.1.0 was supposed to support Java 8.
> 
> \### Actual behavior
> 
> The 'Test authentication' fails in keycloak 16.1.0 when Java 8 is used and produces the error: 'No such method error'.
> !\[ldap-keycloak\](https://user-images.githubusercontent.com/39064501/147195021-6e37d0f9-c235-4809-a66b-78796086dfd8.png)
> 
> 
> 
> \### How to Reproduce?
> 
> Requirements:
> 1. Java 8
> 2. Keycloak 16.1.0
> 
> Steps:
> 1. Create an LDAP configuration in User Federation.
> 2. The 'Test connection' shall work fine.
> 3. 'The 'Test authentication' fails and produces the error 'No such method error'.
> 
> \### Anything else?
> 
> \_No response\_