# LDAP Authentication Error – ActiveSupport::MessagePack::UnserializableObjectError

**URL:** <https://meta.discourse.org/t/ldap-authentication-error-activesupport-unserializableobjecterror/385668>\
**Category:** Bug\
**Tags:** auth-plugins\
**Created:** [October 15, 2025, 9:18am UTC](https://meta.discourse.org/t/ldap-authentication-error-activesupport-unserializableobjecterror/385668 "2025-10-15T09:18:04Z")\
**Posts on this page:** 1\
**Showing post:** 5

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**Author:** ![imbi](https://avatars.discourse-cdn.com/v4/letter/i/f0a364/32.png) [@imbi](https://meta.discourse.org/u/imbi)\
**Post date:** [October 27, 2025, 7:53am UTC](https://meta.discourse.org/t/ldap-authentication-error-activesupport-unserializableobjecterror/385668/5 "2025-10-27T07:53:17Z")

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Hello, it concerns the update to 3.6.0.beta2 and the error only affects newly created accounts (Ldap user create mode) for us. Existing accounts can still log in. Rolling back to 3.6.0.beta1 resolves the issue. The LDAP Auth Plugin has not changed.

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_[View the full topic](https://meta.discourse.org/t/ldap-authentication-error-activesupport-unserializableobjecterror/385668)._