Why did this call fail, and what did it send?

Find a failed Apex call, read the reason, see exactly what the script sent, and compare it with a call that worked.

A Data Mapper or Integration Procedure fails, and the script shows a vague message or nothing at all. The Calls tab lists every Apex call the page makes, decoded, so you can read the real reason and the exact input.

Find the failed call

1. Open the Calls tab and use the page as you normally would. Calls appear as they are made. They are captured only while DevTools is open, so if the list is empty press Reload page to capture from the start and repeat the steps. See Empty list.
2. The number on the tab turns red as soon as any call failed, so you will see it from the other tabs too. See Tab badge.
3. Find the red row. In a long list, tick Failed only (under Advanced) or type the class or method name in the filter box. All Apex calls (next to the filter box) is off by default, so other Apex traffic is hidden; tick it to see every call.
4. Click it. A failed call opens on its Output tab, where the reason is. Press Show more on the failure banner for the rest. See Failed calls.

Read the result carefully

The Result mark, a glyph at every width in the last column of the list, is what the answer says, and the HTTP status is only the transport. A call can come back with HTTP 200 and still have failed: "HTTP 200 · Failed" means Apex returned an error inside a successful response. A grey No response means the browser got no answer at all (aborted or offline). See HTTP vs Result.

See what it sent

1. Open the Input tab. It starts with a line such as "12 keys · 3.4 KB". Right-click any row to copy a value, a key or the OmniScript path. See Trees in the call detail.
2. At 100 KB of input or more, an amber "Input 1.2 MB" tag appears in the first lines (red from 1 MB). A Data Mapper or procedure usually needs only a few keys, so check the largest keys listed. See Oversized input.
3. The Options tab holds the call's settings, such as chainable.

Compare it with a call that worked

1. Press Compare with previous (or d) to see what changed in the input, options and output against the earlier call to the same place.
2. A failed call also gets Compare with last success (or Shift+D), which diffs against the last earlier call that did not fail.
3. These buttons appear only when the same place was called before. Otherwise press b on any call to make it the baseline, then select the failed one.

Each difference is shown for input, options and output. See Compare.

What did the call do to the data?

The Changes tab shows how the script's data JSON changed because of the call: the last read before it ended against the first read within five seconds after. See Changes.

Run it again outside the page

• Copy input copies the bare input as JSON, ready to paste into a test or another tool.
• Copy as Apex (the </> icon) is there for Integration Procedure and Data Mapper calls. It copies an anonymous Apex snippet for the Developer Console. See Copy as Apex.

Which element made the call?

If an element makes this call, the detail pane has a Show in Structure button. There, the element's Calls tab shows what it sends and where the answer lands. See Calls tab.

Turn Mask values on before you copy any of this into a ticket. See Report a problem.

Every control is described in the reference. More guides.