What Is Changing in the LinkedIn Marketing API in October and November 2026?
Two LinkedIn Marketing API versions are being switched off. LinkedIn's changelog lists "202510 - Oct 15, 2026" and "202511 - Nov 16, 2026" under Version Sunset, and its developer pages carry a standing banner: "The Marketing Version 202510 (Marketing October 2025) will be sunset on October 15, 2026." Any tool still sending either version after those dates stops getting normal responses.
This is routine for LinkedIn, which releases a new API version every month, but it lands hard on agencies and B2B teams because almost nobody using LinkedIn ads through software knows which version their tools call. Reporting dashboards, CRM connectors, audience sync tools and in-house scripts all send a version, and the oldest ones in production are usually the ones nobody has touched in a year.
| Version header | Released | Sunset date (LinkedIn's wording) | Status on 2 October 2026 |
|---|---|---|---|
202509 | September 2025 | Sep 15, 2026 | Already sunset |
202510 | October 2025 | Oct 15, 2026 | Sunsets in 13 days |
202511 | November 2025 | Nov 16, 2026 | Sunsets in about six weeks |
202601 | January 2026 | January 15, 2027 | Active |
202609 | September 2026 | September 15, 2027 | Active, latest |
One correction worth making explicit. Some automated summaries of LinkedIn's changelog have mislabelled these as 202610 and 202611. Those versions do not exist yet. The page's own sunset lists name 202510 and 202511, the October and November 2025 releases, and the migration status table confirms both dates.
Explain It Like I Am Five
Every time your software talks to LinkedIn, it says which edition of the rulebook it is reading from, like quoting the year on a phone directory. LinkedIn prints a new directory every month and promises to keep each one working for at least a year. After that, it throws the old directory away. If your tool keeps quoting last year's edition, LinkedIn stops answering it. Nothing about your ads changes. The tool that reads or manages them just goes quiet, and often nobody notices until a report comes back empty.
How Does LinkedIn Marketing API Versioning Work in 2026?
LinkedIn versions its Marketing API by month and identifies each version with a request header. Its versioning page says: "Include a request header with the key 'Linkedin-Version' and set the value to the version (format: YYYYMM)." It adds that "These API versions are supported and stable for a minimum of one year before sunset." Each version is therefore a dated contract with roughly a twelve month life.
The header in LinkedIn's own example looks like this:
-H 'Linkedin-Version: 202601' \Two behaviours matter for anyone running production tooling in 2026. LinkedIn states that "An error response is returned when the version header is missing in the request", and that "An error response is returned when the version header is deprecated (e.g., 202401)." There is no silent fallback to a newer version. A tool sending a sunset version gets an error, not slightly different data.
Who Is Affected by the 202510 and 202511 Sunsets?
Anyone whose software calls the LinkedIn Marketing API with either version header, which is a wider group than developers. Agencies and in-house teams are affected even if they never write code, because the tools they rely on make the calls on their behalf. The risk sits with whoever built or maintains the integration, but the consequence shows up in the marketing team's reports and campaigns.
- Agencies with custom reporting: scripts or BI connectors pulling ad analytics into dashboards for clients.
- B2B teams with CRM sync: integrations sending lead or conversion data between LinkedIn and a CRM.
- Audience and ABM tooling: anything creating or updating matched audiences or company lists.
- Campaign automation: bulk campaign creation, budget pacing or bid tools that manage campaigns through the API.
- Third-party martech platforms: usually maintained by the vendor, but worth confirming in writing rather than assuming.
How Do You Check Which Version Your Tools Use in 2026?
Look for the header value. For code you own, search the codebase and any configuration for the string Linkedin-Version and read the value next to it. For tools you do not own, ask the vendor which Marketing API version they currently send and when they plan to move. The answer you want is a version from 2026, not 202510 or 202511.
- Inventory every LinkedIn integration touching your ad accounts: reporting, CRM, audiences, automation, and any freelancer-built scripts.
- Search owned code and config for
Linkedin-Version, including environment variables and scheduled jobs. - Email each vendor and ask for the version in use and their migration date, in writing.
- Check error logs for version errors after any earlier sunset, such as 202509 on 15 September 2026. An integration that broke then and was patched quietly may be close to the line again.
- Note which tools depend on newer features, because some 2026 capabilities only exist on recent versions.
What Should You Do Before 15 October 2026?
Move every integration to a current version, ideally the latest. LinkedIn's migration guidance is that "To migrate your app from an older version to a later version, simply update the older version's YYYYMM formatted value in the header to the newer version's value." Changing the header is trivial. Testing what changed between versions is the real work, and that is why it should start now rather than on 14 October.
| Step | What to do in 2026 | Why |
|---|---|---|
| 1 | Pick a target version, normally 202609 | The latest buys the longest runway, to 15 September 2027 per LinkedIn's table. |
| 2 | Read the release notes between your version and the target | Fields and behaviours change monthly. |
| 3 | Change the header in a test environment first | Errors appear before they reach client reports. |
| 4 | Re-run the key reports and compare totals | Confirms nothing silently changed in the numbers. |
| 5 | Deploy and diarise the next sunset | Every version you adopt has a known end date. |
If you have questions, LinkedIn routes them through its Developer Support Request Form. The changelog notes that "The Zendesk support path will sunset on June 30th", so older support links in internal runbooks may no longer work.
Why Is Upgrading Worth More Than Avoiding an Outage in 2026?
Because several of LinkedIn's most useful 2026 changes only exist on recent versions. Staying on an old header does not just risk a shutdown. It also leaves capabilities unused that matter for B2B performance, particularly around lead quality and measurement.
- Marketing and sales qualified lead conversion types: LinkedIn states
MARKETING_QUALIFIED_LEADandSALES_QUALIFIED_LEAD"are available starting with the 202608 version onwards." Our Conversions API qualified leads guide explains why they matter. - Hashed name matching: the
hashedFirstNameandhashedLastNamefields arrive "Starting with the 202609 version." - Account-level dynamic UTMs: setting tracking parameters for a whole ad account starts "with the 202608 version."
- Company Intelligence filters and a 365-day lookback: the 365-day window starts with 202606, and LinkedIn notes "Versions 202605 and earlier continue to cap the window at 180 days."
What Are the Common Mistakes in 2026?
- Assuming a tool you pay for is already upgraded. Ask for the version in writing.
- Searching for 202610 or 202611. Those are mislabels from automated summaries. The sunsetting versions are 202510 and 202511.
- Changing the header without testing. The header is one line; behaviour differences are not.
- Upgrading only to the next version. Jumping to 202511 buys about a month. Move to a 2026 version.
- Forgetting freelancer-built scripts. They are the integrations most likely to be on an old version and least likely to be monitored.
- Treating it as a developer problem. The first symptom is usually an empty or incomplete client report.
Key Takeaways for 2026
- LinkedIn Marketing API version 202510 sunsets on 15 October 2026 and 202511 on 16 November 2026.
- Versions are set by the
Linkedin-Versionheader in YYYYMM format and are supported for a minimum of one year. - A sunset or missing header returns an error. There is no automatic fallback.
- Agencies and B2B teams are affected through their tools even if they never write code.
- Check owned code for the header, get vendor answers in writing, test, then deploy.
- Moving to 202608 or later also unlocks MQL and SQL conversion types and other 2026 features.
Distk helps B2B teams across India and internationally audit the integrations behind their LinkedIn reporting and campaigns, and make sure an API sunset never turns into a blank client report. If you are not sure which version your stack calls, that inventory is where we start. Related reading: using LinkedIn Campaign Manager in 2026 and the Google Ads API v22 sunset, which lands the same month.
Every version number, date, field name and error code in this guide is quoted from LinkedIn's own developer documentation on Microsoft Learn as read on 2 October 2026. LinkedIn updates these pages monthly, so confirm against the live changelog before acting.
Sources
- LinkedIn Marketing API, Recent Marketing API Changes (Microsoft Learn), the September, August, July and June 2026 release notes.
- LinkedIn Marketing API, Versioning (Microsoft Learn).
- LinkedIn Marketing API, Migrations and API Migration Status (Microsoft Learn).