Informix Error -753: Access denied - Single user limit has been exceeded.

Reasons / Common Causes

-753 fires when the product's license is configured for single-user use, and more than one concurrent connection is attempted — per the official guidance, this is a licensing-enforcement condition, not a technical fault.

1. A single-user license configuration in effect, with a second connection attempted while the first is still active — per the official guidance, the direct, only cause.
2. A remote connection attempted against a single-user (non-networked) license — per the official guidance, the single-user license specifically doesn't cover networked/remote use at all, regardless of concurrency.

Solutions / Resolution

1. Wait until the current user exits, then try again, per the official guidance, for a local single-user license genuinely limited to one concurrent connection.
2. Don't attempt remote/networked access under a single-user license, per the official guidance — that license type doesn't support it regardless of whether only one user is actually connected.
3. If concurrent or networked access is genuinely needed, obtain the appropriate multi-user/ networked license — this is a licensing decision, not something resolvable technically.

Examples

Checking whether the connection is local or remote

$ onstat -g ses
-- review the session list for the connecting client's hostname/address;
-- a hostname other than the database server's own indicates a remote connection

A single-user license rejects remote connections outright, independent of concurrency.

Diagnostic Checks

1. Confirm whether the connection attempt is local or remote — a single-user license disallows remote connections entirely, separate from the concurrency limit.
2. Check whether another local session is already connected, if the attempt is local.

Related Errors / Related Topics

• -754 — "Cannot access the license file." A related licensing error, about the license file itself being unreadable rather than the license's terms being exceeded.

A licensing-enforcement condition, not a technical fault — confirm whether the issue is concurrency (wait and retry) or remote access (not supported under this license type at all).