Informix Error -750: Invalid distribution format found for table_name.

Cause and resolution

Invalid distribution format found for table_name.

This internal error should not occur unless the database has been corrupted in some way. To rebuild the distribution, use UPDATE STATISTICS. If the error recurs, note all circumstances and contact IBM Informix Technical Support.

Oninit® Troubleshooting Guidance

Reasons / Common Causes

-750 is flagged by the official text as an internal error that shouldn't occur unless the database has been corrupted in some way — the stored data-distribution statistics for the named table are in an unrecognized format.

Corruption of the stored distribution data for the table, per the official guidance — the stated cause, with rebuilding via UPDATE STATISTICS as the documented remediation.
A distribution format mismatch after a version upgrade or downgrade, if distributions were built under a different server version that used an incompatible internal format — a plausible contributor given the "corrupted in some way" framing, though not explicitly named by the sparse official text.

Solutions / Resolution

Rebuild the distribution with UPDATE STATISTICS, per the official guidance — the documented, specific fix:
```
UPDATE STATISTICS MEDIUM FOR TABLE table_name;
```
If this recurs after rebuilding, note all circumstances and contact IBM Informix Technical Support, per the official guidance — recurrence after a rebuild suggests something deeper than a one-time corruption.
Consider running a broader consistency check (oncheck, or tbcheck on pre-7.x servers where oncheck was still named that) on the database if -750 appears alongside other signs of corruption, rather than treating it as an isolated issue.

Examples

Rebuilding the distribution

UPDATE STATISTICS MEDIUM FOR TABLE orders;

Diagnostic Checks

Rebuild the distribution with UPDATE STATISTICS first, per the official guidance's specific, documented fix.
If it recurs, check for broader corruption via oncheck, similar to the -620/-622 family, before escalating.

Related Errors / Related Topics

-640 — "QPlan sanity failure line-number." Another statistics-related internal error where UPDATE STATISTICS is the official guidance's documented first fix.

UPDATE STATISTICS is the documented, specific fix — escalate only if the problem recurs after rebuilding.