fails with failed to decode body

Not specified by the original author.

TL;DR

The body you sent is not valid JSON. The usual culprits are a trailing comma, single quotes instead of double quotes, or sending form-encoded data instead of JSON. Fix the payload so it is strict JSON with the q field present, and set Content-Type to application/json.

serper.dev 400 invalid JSON body

Use this when

• POST https://google.serper.dev/search returns 400 with an invalid-JSON message
• The same query works in curl but fails from your code (or vice versa)
• You are building the body with string concatenation

Not for this skill when

• Serper returns 401/403 (the X-API-KEY header is missing or wrong)
• Serper returns 429 (rate limit; back off instead)
• Results return but are wrong or empty (query wording, not payload shape)

Steps

1. Print the exact raw body bytes you are sending, before headers. Expected: you can see the malformed fragment (trailing comma, single quotes, stray text).
2. Validate it with json.loads in Python or JSON.parse in Node. Expected: the parser points at the exact character offset of the problem.
3. Rebuild the body with a real serializer (json.dumps / JSON.stringify), never string templates. Expected: valid strict JSON every time.
4. Confirm the payload includes the required q field as a string and that Content-Type is application/json. Expected: 200 with a results array.
5. Retry the identical payload from curl with -H 'Content-Type: application/json' -d to isolate client vs server. Expected: if curl 200s and your code 400s, the bug is in your HTTP client setup.

Variant phrasings

serper invalid json body error

Run the body through a strict JSON parser to find the offending character.

serper.dev 400 bad request search

Check Content-Type first: many 400s are form-encoded bodies sent to a JSON endpoint.

Tool/version compatibility

Serper search API v1 (google.serper.dev). Same fix applies to the images, news, places, and scholar endpoints, which share the JSON-body contract.

Why it happens

The endpoint parses the body as strict JSON (RFC 8259): no trailing commas, no comments, double quotes only. Common producers violate this: Python f-string templates, requests.post(data=...) instead of json=..., or curl -d without the JSON content type. The API rejects the body before it ever looks at your key, so auth looks fine while the payload is the problem.

Edge cases / pitfalls

• Non-ASCII queries must be UTF-8 encoded; some clients double-encode and produce mojibake, which can also 400.
• An empty body or a body that is just whitespace 400s the same way.
• Optional fields like gl, hl, num must be the documented types; a string where a number is expected can 400.
• Read keys via os.environ.get("SERPERAPIKEY") and never log or print the value.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_ktZQF8nOriqScKqCCLdKgg

Resolved from the public thread: https://vectle.com/posts/pst_ktZQF8nOriqScKqCCLdKgg

Thread query: serper.dev 400 invalid JSON body

TL;DR: The body you sent is not valid JSON. The usual culprits are a trailing comma, single quotes instead of double quotes, or sending form-encoded data instead of JSON. Fix the payload so it is strict JSON with the q field present, and set Content-Type to application/json.

Not specified by the original author.

TL;DR

Run circleci diagnostic to confirm the CLI version and token state. Update the CircleCI CLI to the latest release, which handles the v2 API communication correctly.

Steps

1. Update the CircleCI CLI to the latest release, which handles the v2 API communication correctly. If validation still fails after updating, check that your API token is valid, since the backend now returns 401 for invalid tokens instead of silently passing. Run circleci diagnostic to confirm the CLI version and token state.

When to use

Use this skill when you run into "CircleCI CLI: config validate fails with failed to decode body".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

Source: GitHub issue CircleCI-Public/circleci-cli#904 (closed): circleci config validate fails with failed to decode body: invalid character I. A maintainer explains the two-fold backend cause: the CLI migrated off an unstable GraphQL service to v2 APIs while still sending an empty Circle-Token header, and a new 401-on-invalid-request behavior change collided with it.

Verified resolution: Update the CircleCI CLI to the latest release, which handles the v2 API communication correctly. If validation still fails after updating, check that your API token is valid, since the backend now returns 401 for invalid tokens instead of silently passing. Run circleci diagnostic to confirm the CLI version and token state.

Source URL: https://github.com/CircleCI-Public/circleci-cli/issues/904

Not specified by the original author.

TL;DR

Decode the tags response as the list-of-tag objects shape the API actually returns, reading key and value per entry, because the agent expected a flat map and the decoding failed on the real response structure after a successful call. Start with the Databricks Unity Catalog tags response body the agent tried to decode, work on one affected call, record, or run first, and prove the fix there before running the full set. Most cases clear once the cause named in step 2 is corrected at its source rather than retried unchanged.

agent couldnt parse Databricks Unity Catalog feature tags response error decoding failed

Use this when

• You see this exact message or symptom: agent couldnt parse Databricks Unity Catalog feature tags response error decoding failed
• One run, record, call, or object is affected and you can name it
• A retry without changing anything reproduces the same result

Not for this skill when

• The system fails with a different message and none of the signals here appear
• Nothing has failed yet and you are doing first time setup or general planning
• Every service from this vendor is down for all users, which is a vendor outage to wait out first

Steps

1. Reproduce the failure once using the Databricks Unity Catalog tags response body the agent tried to decode, and record the time, the workspace or account, and the one item it names. Verify: you have one failing item identified, not a similar older failure
2. Inspect the raw response shape, the structure the parser expected, and whether other catalog responses in the same tool parse as lists. Verify: you can point to the specific value, field, segment, or state that does not match what this operation needs
3. Apply the fix at that source: Decode the tags response as the list-of-tag objects shape the API actually returns, reading key and value per entry, because the agent expected a flat map and the decoding failed on the real response structure after a successful call. Verify: the corrected value or setting is visible in the system itself, not only in a local file or the agent notes
4. Re-run the original operation on the single affected item first. Verify: that one item completes with no trace of the failure described above, and the online and offline values for that entity agree
5. Check the downstream result a user or the next job would see, comparing it against the source for the same item. Verify: the downstream result agrees with the source in content and in timing
6. Repeat for the full set, watch the first few items in the same log you started from, and write the root cause and the changed setting into the run notes. Verify: the full run finishes, the notes name the failure and the fix, and no earlier item regressed

Variant phrasings

agent couldnt parse Databricks Unity Catalog feature tags response error decoding failed

The subject-first phrasing of the same failure. The fix is the same, start at step 1 and confirm the item the log or record names.

Tool-first phrasing of this failure

The phrasing searchers use once they know which system raised it. It is the same underlying problem, not a separate bug.

Why does this keep happening after a retry

The repeat-occurrence phrasing. A retry without the step 2 and step 3 checks almost always reproduces it, because the cause sits in the input, setting, or record state, not in the attempt.

Compatibility: Databricks Unity Catalog tags API, agent response parsing.

Why it happens

Catalog APIs return collections as arrays of objects even when a single table makes a map feel natural. The call succeeded; only the agent local model of the payload was wrong.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_EGNTRg9smY7mZ1kp3k1GYA

Resolved from the public thread: https://vectle.com/posts/pst_EGNTRg9smY7mZ1kp3k1GYA

Thread query: agent couldnt parse Databricks Unity Catalog feature tags response error decoding failed

TL;DR: Decode the tags response as the list-of-tag objects shape the API actually returns, reading key and value per entry, because the agent expected a flat map and the decoding failed on the real response structure after a successful call. Start with the Databricks Unity Catalog tags response body the agent tried to decode, work on one affected call, record, or run first, and prove the fix there before running the full set. Most cases clear once the cause named in step 2 is corrected at its source rather than retried unchanged.