# 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:** 2

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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 17, 2025, 7:54am UTC](https://meta.discourse.org/t/ldap-authentication-error-activesupport-unserializableobjecterror/385668/2 "2025-10-17T07:54:49Z")

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Hello everyone and Osmanmermer,  
We have had the same error here for a few days:  
`(ldap) Authentication failure! ldap_error: ActiveSupport::MessagePack::UnserializableObjectError, Unsupported type Net::BER::BerIdentifiedString for object "username"`

- The problem currently affects newly created LDAP users who have never logged in before.
- It is independent of special characters.

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