LDAP result code 20 means the requested change would create a conflict with an attribute or value already in the target entry. Read the server’s complete diagnostic, inspect the entry, then remove a duplicate, use the correct replace or delete operation, or correct the schema and object-class rules before retrying.
What “DS attribute or value exists” means
“DS attribute or value exists” is LDAP result code 20. ForgeRock Directory Services defines it as a failed operation that would conflict with an attribute or attribute value already present in the target entry. The usual example is an add modification that tries to put a second value into an attribute defined as single-valued.
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“The requested operation failed because it would have resulted in a conflict with an existing attribute or attribute value in the target entry.” — ForgeRock Directory Services LDAP Guide, Schema Errors section.
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This is a directory-data or schema conflict, not a generic network-connectivity failure. The server received the request, evaluated it against the entry and its schema, and rejected the resulting state. A successful fix therefore depends on the exact distinguished name (DN), attribute, value and modification type in the diagnostic message.
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Read the complete diagnostic before changing anything
The number 20 tells you the class of failure, but the additional server text normally points to the entry, attribute or value that caused the conflict. Capture the full output from the client, application log or Directory Server access log. Do not rely on a shortened message shown by a graphical administration tool.
- Record the target DN, such as
uid=alice,ou=people,dc=example,dc=com. - Record the attribute named in the request, such as
mail,telephoneNumberor a custom attribute. - Record whether the request used
add,replaceordelete. - Copy the value being sent, including capitalization, spaces and any normalization-relevant formatting.
- Note whether the request is generated by an LDIF file, an application, a synchronization job or an administrative console.
If the diagnostic names a different attribute than the one you expected, investigate the generated request rather than editing the wrong field. A synchronization process may be submitting several modifications in one transaction, and the failing operation can be later in the batch than the line you first noticed.
Inspect the target entry safely
Query the entry identified by the error before retrying the write. A base-scope search asks for exactly that entry and avoids confusing a similarly named object elsewhere in the directory.
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-b "uid=alice,ou=people,dc=example,dc=com"
-s base "(objectClass=*)" mail objectClassUse your environment’s secure LDAP endpoint and an account authorized to read the entry. The command above requests the suspected attribute and the entry’s object classes; include any other attribute named by the diagnostic. If your server requires StartTLS or a different authentication mechanism, use the corresponding client options rather than sending credentials over an unsuitable connection.
Compare the returned values with the request byte-for-byte where relevant. LDAP servers apply attribute syntax and matching rules, so two strings that look different to a person can still compare as the same value after normalization. Conversely, values that differ in a meaningful way may both be legal for a multi-valued attribute.
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Choose the correct fix
Use the combination of cardinality, current data and intended final state to choose an operation. The safest change is the smallest one that produces the desired entry.
| What you find | Why the request failed | Correct action | Risk to check |
|---|---|---|---|
| The exact value is already present | add would create a duplicate |
Remove that value from the payload, or skip the modification | Make sure the application is not repeatedly submitting the same add |
| A different value exists and the attribute is single-valued | A second value is not allowed | Use replace with the one intended value |
Replacing removes the old value; confirm that is intended |
| A different value exists and the attribute is multi-valued | The value may be duplicated after normalization, or the request may violate another constraint | Inspect matching rules and send only a distinct, permitted value | Check server schema and application assumptions |
| The attribute is not permitted by the entry’s object classes | The resulting entry would violate schema | Use an object class that permits the attribute, or redesign the schema and update the entry accordingly | Test schema changes privately before production |
| The attribute name is undefined | The server has no matching schema definition | Define the attribute through the directory’s supported schema process, then assign an appropriate object class | Do not create conflicting or incompatible definitions |
Fix a duplicate value in an LDIF or application payload
Remove an already-present value from an add request
If the entry already contains the value, delete that line from the generated LDIF or change the application so it does not submit the same add again. For example, this request is unsafe when mail: [email protected] is already present:
dn: uid=alice,ou=people,dc=example,dc=com
changetype: modify
add: mail
mail: [email protected]
-Removing the modification is preferable to deleting the existing directory value merely to make the add succeed. If the operation is part of an idempotent provisioning workflow, make the workflow read the current state and treat an already-present value as success.
Replace a changed single value
When the intent is to change a single-valued attribute, submit one replacement value instead of adding a second value.
dn: uid=alice,ou=people,dc=example,dc=com
changetype: modify
replace: employeeNumber
employeeNumber: 84721
-Before using replace, verify that the attribute is actually single-valued and that removing the old value will not break an application or referential process. A replacement expresses the desired final state; it is not a way to preserve both values.
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Delete a value deliberately
If a value is obsolete, remove it with a targeted delete. Include the value when you want to remove only that value from a multi-valued attribute:
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dn: uid=alice,ou=people,dc=example,dc=com
changetype: modify
delete: telephoneNumber
telephoneNumber: +1 555 0100
-A delete without a value has broader effect: it removes the entire attribute. Use that form only when every value should be removed and the schema permits the attribute to be absent.
Verify single-valued versus multi-valued cardinality
LDAP schema definitions specify whether an attribute may have one value or multiple values. A single-valued attribute cannot receive a second value, even if the two values appear useful. Typical fixes are to send only one value or to use replace when the old value should be changed.
For a multi-valued attribute, multiple distinct values can be valid, but duplicates are still a problem. Matching rules can treat differences in case, spacing or formatting as equivalent. Inspect the schema’s syntax and matching rule rather than assuming that textual differences make two values unique.
Do not infer cardinality from what an administration console happens to display. Check the active schema on the server that rejected the request. Replicated or staged environments can also differ if schema deployment was incomplete, so compare the server configuration when the same LDIF succeeds in one environment and fails in another.
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Check object classes and schema permissions
Every attribute in the resulting entry must be defined in the server schema and permitted by at least one object class assigned to that entry. A request can therefore fail even when the attribute value is not visibly duplicated: the entry may not be allowed to hold the attribute, or the attribute definition may be missing.
- Read the entry’s current
objectClassvalues along with the failing attribute. - Confirm that the attribute name is defined on the Directory Server handling the write.
- Identify an appropriate structural or auxiliary object class that permits the attribute.
- Determine whether that object class is compatible with the entry’s existing structural class and required attributes.
- Apply the object-class or schema change in a private Directory Server first, then repeat the exact client operation there.
ForgeRock’s schema guidance recommends testing schema changes and scripts on a private Directory Server, adapting applications to avoid schema violations, and requesting schema updates that do not conflict with definitions already in use. Do not copy a definition from another directory without checking its OID, syntax, matching rules, single- versus multi-valued setting and compatibility with the definitions already loaded on this server.
Use extensibleObject only as a last-resort workaround
The auxiliary extensibleObject object class can allow an entry to hold user attributes that would otherwise be undefined or not permitted by its current object classes. ForgeRock warns that relying on it can be abused and can reduce interoperability. It may let a write succeed while leaving the directory with weakly governed data that other LDAP clients, synchronization tools or future schema changes do not understand.
Prefer a proper schema definition and an object class designed for the attribute. Consider extensibleObject only when no better schema design is available, document why it is needed, restrict who can write the custom attributes, and test every consuming application before deployment.
Retry the operation in a controlled sequence
- Export or otherwise preserve the current entry and the original LDIF so you can audit or reverse the change.
- Make one correction only: remove the duplicate, change
addtoreplace, target a precisedelete, or correct the schema/object class. - Run the modified request against a private or non-production Directory Server first.
- Read the entry back and verify the complete resulting state, including
objectClassand all affected values. - Run the same request in production during an approved change window, using the least-privileged account that can perform it.
- Read the production entry again and retain the server response and resulting LDIF in your change record.
Testing the entire transaction matters when an LDIF file contains multiple modifications. A correction to one line can expose a second conflict later in the request, while an application may retry automatically and recreate the original duplicate. Temporarily pause the job or fix its idempotency logic before repeatedly applying the same payload.
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Common failure patterns and their remedies
An add operation is retried after a timeout
A client may time out after the server committed a change, then retry the same add. The retry sees the value already present and returns result code 20. Read the entry before retrying and make the provisioning action idempotent: an existing desired value should be treated as the target state, not as a reason to submit another add.
The LDIF contains the same value twice
Generated files can include duplicate lines for one attribute, especially when data is merged from multiple sources. De-duplicate the payload before sending it and correct the generator so the issue does not recur.
A synchronization rule maps two sources to one single-valued attribute
If two source records map to a single-valued directory attribute, the connector must define precedence or reject the record before issuing LDAP modifications. Do not convert a single-valued attribute to multi-valued merely to hide an unresolved identity or data-model conflict.
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Compare schema definitions, object classes, matching rules and server versions across the environments. A schema extension may exist only in the test server, or replication may not have distributed it to every production writer. Apply the same tested schema package through the approved deployment process rather than editing one server ad hoc.
A console reports only “attribute or value exists”
Switch to a client or server log that exposes the full diagnostic, identify the exact modification inside the transaction, and inspect the entry with a base-scope search. The short label alone cannot tell you whether the conflict is a duplicate value, a single-value violation or a related schema problem.
How to prevent result code 20
- Design provisioning operations to be idempotent: read or compare current state before adding values.
- Use
replacefor intentional changes to single-valued attributes instead of adding a new value first. - Validate LDIF in a private Directory Server with the same schema and object classes used in production.
- Keep schema definitions under change control and deploy them consistently to every server that can receive writes.
- Have synchronization jobs detect duplicate source data and conflicting mappings before they generate LDAP modifications.
- Log the DN, attribute, operation and server diagnostic for failed writes, while protecting credentials and sensitive values.
- After each automated change, read back the entry and compare it with the intended state.
Decision checklist
- Did you capture the complete diagnostic, not only the number 20?
- Did you inspect the exact target DN and attribute with a base-scope search?
- Is the value already present, including after the server’s matching-rule normalization?
- Is the attribute single-valued or multi-valued in the active schema?
- Should the final state retain the old value, replace it, or remove it?
- Are the attribute and every object class defined and allowed on this entry?
- Did you test the corrected LDIF, application logic or schema on a private Directory Server?
- Could an automatic retry or synchronization mapping recreate the conflict?
- Have you read the entry back after the change and recorded the result?
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What the error tells you—and what it does not
Result code 20 confirms that the requested result conflicts with an existing attribute or value under the server’s rules. It does not by itself identify whether the duplicate came from the LDIF, an application retry, a synchronization mapping or schema cardinality. The reliable path is to inspect the diagnostic and entry, establish the schema rules, choose the operation that expresses the intended final state, and validate the change privately before production.
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