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Informix Error -491

-491 DBNLS not set (LC_COLLATE must be string_value).

Set the DBNLS environment variable to an appropriate value. Make sure LC_COLLATE is set to the specified string_value.

Oninit® Troubleshooting Guidance

Reasons / Common Causes

-491 is an NLS-environment-configuration error, closely related to -490: the DBNLS environment variable isn't set, and the specific LC_COLLATE value the database requires is named directly in the error message.

  1. DBNLS not set at all in the environment of the session/application connecting to an NLS-enabled database.
  2. LC_COLLATE set to a value that doesn't match what the database actually requires — the error message itself names the expected string_value.
  3. Environment variables configured for one database's locale requirements, while the application also connects to a different NLS-enabled database expecting a different LC_COLLATE.
Solutions / Resolution
  1. Set the DBNLS environment variable to an appropriate value, per the official guidance.
  2. Ensure LC_COLLATE is configured to the specific string value named in the error message, per the official guidance — this isn't a generic locale setting but one tied to the specific NLS-enabled database being connected to.
  3. For applications connecting to multiple NLS-enabled databases with different locale requirements, set these environment variables per-connection rather than globally, if the requirements genuinely differ.
Examples
Setting DBNLS and LC_COLLATE
export DBNLS=1
export LC_COLLATE=en_us.utf8
-- use the exact value named in the error message, not a
-- generic or assumed locale string
Diagnostic Checks
  1. Check whether DBNLS is set in the connecting session's environment.
  2. Check LC_COLLATE's current value against the specific string_value named in the error message.
Related Errors / Related Topics
  • -490 — "Database was created without NLS functionality." The base condition this error's environment-configuration requirement applies to — an NLS-enabled database needing matching client-side locale environment variables.
  • -445 — "The length of the collation name in the SET COLLATION statement exceeds 32 bytes." A related collation-configuration restriction, in a different context (an explicit SET COLLATION statement rather than environment variables).

Use the exact string_value the error message names for LC_COLLATE — this is tied to the specific NLS-enabled database being connected to, not a generic system locale.