The July 2026 Marketo release put two AI skills in the headlines. The thing that will actually break your instance is quieter and it has dates on it: two Marketo API changes take effect on July 31, 2026, and a third follows on August 31. If any integration you rely on is more than a couple of years old, at least one of them touches you.

Marketo API breakers across two dates: on July 31, 2026 the SOAP API is shut off and Merge Leads caps at 25 IDs per call, and on August 31 the REST access_token query-string parameter is removed
The AI skills made the headlines. These three API changes are what actually break things.

I have run marketing operations on Marketo long enough to know the pattern. The feature announcements get the attention. The deprecation notes, buried in the same release, are the ones that page you at the wrong hour. So let me take both in order: what shipped, then what you have to fix before the end of the month. Everything here traces to Adobe's own Marketo Engage release notes, not a vendor blog summary.

What actually shipped in the July 2026 release

Marketo ships monthly. The July 2026 release started its phased rollout on July 10, 2026, with the notes last updated June 18. The headline items are two new Marketo AI skills, both in open beta: Product Knowledge, which answers natural-language questions using Adobe's own documentation without leaving the platform, and Investigate Leads, which explains in plain language why a specific person did not reach a milestone like MQL or program qualification.

These sit inside Marketo AI, an agent-based assistant that has been in open beta since June 18, 2026. The skill set also includes Validate Programs, which flags setup problems before you launch, and Import Leads, which imports and deduplicates with field mapping. Access is not automatic: per the Marketo AI overview, you go through your account manager and sign an AI-terms agreement first.

Marketo's four AI agent skills in open beta: Investigate Leads, Product Knowledge, Validate Programs, and Import Leads Investigate Leads Explain why a lead did not reach a milestone like MQL Product Knowledge On-demand Marketo answers drawn from Adobe's own docs Validate Programs Flag setup problems in a program before you launch Import Leads Import and dedupe records with field mapping Open beta · since Jun 18, 2026
The four Marketo AI agent skills, all in open beta. Access is gated by your account manager.

Read that word again: beta. Not general availability. The rollout was still in progress on the day I write this, so the skills may not be visible in every instance yet, and one or two search-engine summaries floated a "GA" framing that the actual release notes do not support. Treat Investigate Leads as a preview of where Marketo is heading, an operations assistant you talk to in plain English, not a feature you rebuild your process around this quarter.

The part that will actually break things: API changes across two dates

Here are the deadlines that belong on your calendar. Two API changes take effect on July 31, 2026, and a third follows a month later on August 31, all confirmed in Adobe's current release notes. Do not let the split dates lull you: the July 31 pair is the one that arrives first.

  • The SOAP API is gone (July 31). Support for the Marketo SOAP API ends entirely. Any service still calling SOAP has to move to REST. This deadline has slipped before, from an original January 31 to March 31 and now to July 31, so if you have been waiting it out, the waiting is over.
  • Merge Leads caps at 25 IDs (July 31). A Merge Leads call with more than 25 IDs in the leadIds parameter now returns error 1080 and the call is skipped, not truncated. Batch your merges to 25 or fewer.
  • The REST access_token query parameter is removed (August 31). Passing the token as a URL query parameter stops working. You move it into the header. In practice you replace -F access_token=<token> with -H "Authorization: Bearer <token>".

One more lands later. From September 30, 2026, a Get Lead Activities or Get Lead Changes call that targets a static list of 10,000 or more leads returns error 1003. If you pull activity data by list, this one is coming for you next.

The Marketo deprecation checklist: SOAP API ends and Merge Leads calls over 25 IDs fail on July 31, the access_token query parameter is removed on August 31, then on September 30 large Get Lead Activities calls fail JUL 31 SOAP API support ends Migrate integrations to the REST API JUL 31 Merge Leads calls over 25 IDs now fail Calls with more than 25 lead IDs return error 1080 AUG 31 access_token query param removed Send the Authorization: Bearer header instead SEP 30 Get Lead Activities fails on large lists Static lists of 10,000+ leads now return error 1003
The four API changes to clear before the deadlines. Source: Adobe Marketo Engage release notes.

What to do before the deadlines

None of this is hard. It is just work that has to happen before each date, not after. Here is the order I would run it in.

  • Audit for SOAP. List every integration, iPaaS connector, and homegrown script that touches Marketo. Flag anything using the SOAP endpoint and migrate it to the equivalent REST call. Adobe publishes a SOAP-to-REST mapping in its developer docs.
  • Grep for access_token= in query strings. Search your integration code and any middleware for the token passed as a URL parameter. Move it to the Authorization: Bearer header. This is a small change that fails loudly if you miss it, so test each caller.
  • Find your Merge Leads calls and batch them. Cap every call at 25 IDs and add handling for error 1080 so a big dedupe job does not silently skip records.
  • Then, before September 30, check list-based activity pulls. Anything reading activities or changes off a static list of 10,000-plus leads needs a different approach or pagination, and handling for error 1003.

Do this in a sandbox first, and read the live release notes rather than a cached summary, because the deprecation dates on this platform have a history of moving. July 31 for SOAP and Merge Leads, and August 31 for the access_token change, are the current authoritative dates. July 31 is also the third date they have given for SOAP, so verify before you plan around it.

Two more things worth knowing

The built-in SEO tile is already gone. Marketo deprecated its Search Engine Optimization feature on March 31, 2026 and removed the tile on April 1. If you exported your keyword results and competitor trends before the deadline, good. If you did not, that data is not coming back. This is the standing argument against leaning on a platform's bolt-on tool for a job it does not really own. Your deliverability and content checks should live somewhere you control, which is part of why I keep the deliverability checker and the rest of the stack outside any one platform.

Project Falco opened for beta. Posted June 12, 2026, it is a roughly six-week beta running from late June into early August that delivers agentic AI through an updated Adobe Journey Optimizer B2B Edition integrated with Marketo Engage, with no purchase required during the beta. If your team is invested in Marketo long term, it is worth watching, because it signals the direction: Adobe is folding Marketo into the larger Journey Optimizer story. And a smaller quality-of-life win from February, folder management in the Email Designer, finally added share, archive, cross-workspace sharing, and drag-and-drop for assets.

What marketers should expect and do

Split it into two tracks. The near-term track is pure operations hygiene: finish the SOAP migration and batch your merges before July 31, then move your auth into the header before August 31. This is not optional and it is not glamorous, and it is exactly the kind of work that decides whether your Monday looks calm or not. The longer track is the AI story: request beta access through your account manager, run Investigate Leads against a real "why did this good lead never convert" question, and judge the answer yourself before you believe the demo.

If you are standing Marketo up from scratch rather than maintaining it, the sequence matters more than any single feature. I wrote the full setup order in the Marketo onboarding guide, and the same principle applies here: get the plumbing right before you chase the new thing.

So the honest question for your team this week is not whether the new AI skills are exciting. It is simpler than that: do you actually know which of your integrations still call the SOAP API or pass a token in a query string, and are you sure they will still work on August 1?

, Amit