A Next.js site packaged for Cloudflare with OpenNext has a date on it that nobody prints: two years after the major's release, OpenNext refuses to build it. Your site keeps running. Your fixes stop shipping. Paste a package.json and get the date.
On 2026-10-21 at 00:00 UTC, every build of one Flint makerspace's website started failing at the packaging step. Nothing in the code had changed overnight. Next.js 15 had been released on 2024-10-21, OpenNext's build step checks the release date against the clock, and that night the major turned two. The support calendar everyone reads (endoflife.date, the Next.js support policy) said the same date, but it said "security fixes end", and the people reading it, humans and machines, had agreed a week earlier that nothing would break on the day. Fixes ending is a policy. Builds failing is a wall.
The date is not on any website you would check. It is in a table inside the packaging tool itself.
The table below is the one shipped in @opennextjs/aws 4.1.11 (read 2026-10-21). Yours is the one that counts, because the build runs with yours. From your project folder:
node -e "const f=require('fs');const p=require.resolve('@opennextjs/aws/dist/build/helper.js',{paths:[process.cwd()]});const m=f.readFileSync(p,'utf8').match(/NEXT_RELEASE_DATES\s*=\s*\{([^}]*)\}/);console.log(m?m[1].trim():'table not found in '+p)"A major your installed table does not list is refused at once, before any date: the tool treats an unknown major as unsupported. That is what makes a jump to a brand-new major fail on day one with an OpenNext that predates it.
| Next.js major | released | OpenNext builds it until |
|---|
OpenNext has a switch, opennextjs-cloudflare build --dangerouslyUseUnsupportedNextVersion, that turns the refusal into a warning. It gets your fixes shipping again the same hour. It does not make the old major any safer, and it hides the only mechanical reminder you had: the next time anyone will notice the version is the next security advisory. Put a date next to the switch when you add it.