What prometheus/prometheus shipped

Week of September 14, 2026

What shipped

• Version 3.15.0-rc.0 released with changes to range query evaluation to prevent subqueries from evaluating past the parent's last actual step. Release
• Extended range selectors are now enabled by default in PromQL. Pull request #19697
• Parser options for stable PromQL features have been removed. Pull request #19704
• Experimental search API endpoints are now clamped to 1000 results. Pull request #19731
• Fixed typo in remote write v1 native histogram with custom buckets drop log message. Pull request #19752
• WAL buffers are now reset after write errors to prevent invalid WAL records in agent. Pull request #19700
• Duplicate staleness tracking in AppenderV2 scraping has been removed for performance. Pull request #19702
• Range vector functions no longer raise spurious labelset collision errors for series with different metric names. Pull request #18631
• Search API now returns lexically smallest label values when hitting result limits. Pull request #19694
• Sum-only classic histograms are now rejected during NHCB conversion unless they have explicit count or buckets. Pull request #19315

Why it matters

Version 3.15.0-rc.0 is now available with significant PromQL improvements including enabled extended range selectors and corrected range query behavior. Multiple performance optimizations reduce unnecessary work in scraping and storage, while bug fixes address histogram conversion, staleness detection, and API result consistency.

Changelog entry

• [CHANGE] PromQL: Range queries no longer cause subqueries to evaluate past the parent's last actual step, fixing query stats inflation and sample limit calculation. Release
• [CHANGE] PromQL: Extended range selectors are now enabled by default. Pull request #19697
• [CHANGE] PromQL: Removed parser options for stable features. Pull request #19704
• [CHANGE] API: Clamped experimental search endpoints to 1000 results. Pull request #19731
• [BUGFIX] PromQL: Range vector functions no longer raise spurious labelset collision errors when series have different metric names but same remaining labels. Pull request #18631
• [BUGFIX] Storage/Remote: Fixed typo in native histogram with custom buckets drop log message. Pull request #19752
• [BUGFIX] TSDB/Agent: WAL buffers are now reset after write errors to prevent invalid checksummed WAL records. Pull request #19700
• [BUGFIX] Search API: Returns lexically smallest label values when hitting result limits. Pull request #19694
• [BUGFIX] Conversion: Sum-only classic histograms are now rejected during NHCB conversion unless they have explicit count or buckets. Pull request #19315
• [BUGFIX] API: Fixed duration parsing that overflowed at int64 boundary. Pull request #19658
• [PERF] Scrape: Removed duplicate staleness tracking in AppenderV2. Pull request #19702
• [PERF] Scrape: Removed unused series cache hashes. Pull request #19703