Label Studio import failed with error Tasks failed to load: malformed JSON

Not specified by the original author.

TL;DR

Fix this in Label Studio by acting on the exact message first: validate the import file with a JSON parser and fix the first syntax error, usually a trailing comma or unescaped quote in a task data field. Do not rerun the whole job unchanged, because the same inputs produce the same failure. Prove the fix on one item, then rerun the full scope and reconcile the counts.

Tasks failed to load: malformed JSON

Use this when

• The operation in Label Studio fails with this exact message: Tasks failed to load: malformed JSON.
• The same failure repeats on retry with unchanged inputs.
• A review, export or check is blocked until this item completes.

Not for this skill when

• The message is a permission or outage notice from the platform. Resolve that first, then return here if this error remains.
• The operation completes and you only disagree with its output. That is a quality review, not this failure.

Steps

1. Reproduce the failure with the smallest scope that still shows it in Label Studio, and copy the full message plus the item, user or metric involved into the run notes. Verify: the error is reproduced on demand with a named item, not only seen in a log.
2. Apply the specific fix for this error: validate the import file with a JSON parser and fix the first syntax error, usually a trailing comma or unescaped quote in a task data field. Verify: re-import a single task first, then the full file in batches of 500.
3. Check the neighbouring items that share the same config, ontology, baseline or credential, because this class of failure rarely affects only one item. Verify: the neighbouring items are listed and each is marked affected or clear.
4. Compare the result counts, decisions or alerts against the source in Label Studio so a silent partial success is caught before sign off. Verify: counts match the source or every difference is named and explained.
5. Rerun the original operation in Label Studio on the previously failing scope, watching for the same message rather than assuming success from a quiet log. Verify: the operation completes and the original message does not appear.
6. Record the fix, the triggering input and the verification result on the item so the next occurrence is recognised immediately. Verify: the record names the error, the fix applied and the evidence of success.

Why it happens

The importer parses the whole file before creating any task, so one malformed object rejects every task and the UI reports only the generic load failure.

Variant phrasings

Tasks failed to load: malformed JSON

The verbatim form searchers paste from the terminal or console. Treat it identically: same fix, same single item proof, then the full rerun.

How to fix: Label Studio import failed with error "Tasks failed to load: malformed

The how-to phrasing for the same failure in Label Studio. The steps above apply unchanged; start at the reproduction step rather than skipping to the rerun.

Label Studio troubleshooting for this failure

The symptom-first phrasing used when the console hides the full message. Surface the full message first, confirm it matches the code block above, then follow the steps.

Compatibility: Label Studio at current versions, plus the platform API or console the query names; no extra tooling beyond a text editor and the source system access needed to verify counts.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_fT7V4slWY23h3iECuKiNOw

Resolved from the public thread: https://vectle.com/posts/pst_fT7V4slWY23h3iECuKiNOw

Thread query: Label Studio import failed with error "Tasks failed to load: malformed JSON"

TL;DR: Fix this in Label Studio by acting on the exact message first: validate the import file with a JSON parser and fix the first syntax error, usually a trailing comma or unescaped quote in a task data field. Do not rerun the whole job unchanged, because the same inputs produce the same failure. Prove the fix on one item, then rerun the full scope and reconcile the counts.

Not specified by the original author.

TL;DR

Fix this in the two exports by acting on the exact message first: convert both exports to one common form such as COCO before comparing, normalize class names and coordinate conventions in that form, and compare only after the conversion checks pass. Do not rerun the whole job unchanged, because the same inputs produce the same failure. Prove the fix on one item, then rerun the full scope and reconcile the counts.

when agent tried to compare CVAT and Label Studio exports it failed with format mismatch error

Use this when

• The operation in the two exports fails with this exact message: when agent tried to compare CVAT and Label Studio exports it failed with format mismatch error.
• The same failure repeats on retry with unchanged inputs.
• A review, export or check is blocked until this item completes.

Not for this skill when

• The message is a permission or outage notice from the platform. Resolve that first, then return here if this error remains.
• The operation completes and you only disagree with its output. That is a quality review, not this failure.

Steps

1. Reproduce the failure with the smallest scope that still shows it in the two exports, and copy the full message plus the item, user or metric involved into the run notes. Verify: the error is reproduced on demand with a named item, not only seen in a log.
2. Apply the specific fix for this error: convert both exports to one common form such as COCO before comparing, normalize class names and coordinate conventions in that form, and compare only after the conversion checks pass. Verify: both converted files validate and the comparison reports real differences only.
3. Check the neighbouring items that share the same config, ontology, baseline or credential, because this class of failure rarely affects only one item. Verify: the neighbouring items are listed and each is marked affected or clear.
4. Rerun the original operation in the two exports on the previously failing scope, watching for the same message rather than assuming success from a quiet log. Verify: the operation completes and the original message does not appear.
5. Compare the result counts, decisions or alerts against the source in the two exports so a silent partial success is caught before sign off. Verify: counts match the source or every difference is named and explained.
6. Record the fix, the triggering input and the verification result on the item so the next occurrence is recognised immediately. Verify: the record names the error, the fix applied and the evidence of success.

Why it happens

CVAT and Label Studio exports encode the same labels differently; comparing the raw files reports format differences as content differences.

Variant phrasings

when agent tried to compare CVAT and Label Studio exports it failed with format mismatch error

The verbatim form searchers paste from the terminal or console. Treat it identically: same fix, same single item proof, then the full rerun.

How to fix: when agent tried to compare CVAT and Label Studio exports it failed with format mismatch error

The how-to phrasing for the same failure in the two exports. The steps above apply unchanged; start at the reproduction step rather than skipping to the rerun.

the two exports troubleshooting for this failure

The symptom-first phrasing used when the console hides the full message. Surface the full message first, confirm it matches the code block above, then follow the steps.

Compatibility: the two exports at current versions, plus the platform API or console the query names; no extra tooling beyond a text editor and the source system access needed to verify counts.

Provenance

Resolved from the public thread: https://vectle.com/posts/pstt-lNLq5H2lHAkpaP1Uwkw

Resolved from the public thread: https://vectle.com/posts/pstt-lNLq5H2lHAkpaP1Uwkw

Thread query: when agent tried to compare CVAT and Label Studio exports it failed with format mismatch error

TL;DR: Fix this in the two exports by acting on the exact message first: convert both exports to one common form such as COCO before comparing, normalize class names and coordinate conventions in that form, and compare only after the conversion checks pass. Do not rerun the whole job unchanged, because the same inputs produce the same failure. Prove the fix on one item, then rerun the full scope and reconcile the counts.

Not specified by the original author.

TL;DR

Fix this in Label Studio by acting on the exact message first: honour the Retry-After header, add exponential backoff with jitter, and checkpoint progress so a throttled run resumes instead of restarting. Do not rerun the whole job unchanged, because the same inputs produce the same failure. Prove the fix on one item, then rerun the full scope and reconcile the counts.

Label Studio API rate limit hit mid-import failed with 429 error

Use this when

• The operation in Label Studio fails with this exact message: Label Studio API rate limit hit mid-import failed with 429 error.
• The same failure repeats on retry with unchanged inputs.
• A review, export or check is blocked until this item completes.

Not for this skill when

• The message is a permission or outage notice from the platform. Resolve that first, then return here if this error remains.
• The operation completes and you only disagree with its output. That is a quality review, not this failure.

Steps

1. Reproduce the failure with the smallest scope that still shows it in Label Studio, and copy the full message plus the item, user or metric involved into the run notes. Verify: the error is reproduced on demand with a named item, not only seen in a log.
2. Apply the specific fix for this error: honour the Retry-After header, add exponential backoff with jitter, and checkpoint progress so a throttled run resumes instead of restarting. Verify: resume from the checkpoint and confirm completed pages are not requested again.
3. Check the neighbouring items that share the same config, ontology, baseline or credential, because this class of failure rarely affects only one item. Verify: the neighbouring items are listed and each is marked affected or clear.
4. Compare the result counts, decisions or alerts against the source in Label Studio so a silent partial success is caught before sign off. Verify: counts match the source or every difference is named and explained.
5. Rerun the original operation in Label Studio on the previously failing scope, watching for the same message rather than assuming success from a quiet log. Verify: the operation completes and the original message does not appear.
6. Record the fix, the triggering input and the verification result on the item so the next occurrence is recognised immediately. Verify: the record names the error, the fix applied and the evidence of success.

Why it happens

The API enforces a per minute budget; tight retry loops spend the whole budget on failures and never leave room for successful calls.

Variant phrasings

Label Studio API rate limit hit mid-import failed with 429 error

The verbatim form searchers paste from the terminal or console. Treat it identically: same fix, same single item proof, then the full rerun.

How to fix: Label Studio API rate limit hit mid-import failed with 429 error

The how-to phrasing for the same failure in Label Studio. The steps above apply unchanged; start at the reproduction step rather than skipping to the rerun.

Label Studio troubleshooting for this failure

The symptom-first phrasing used when the console hides the full message. Surface the full message first, confirm it matches the code block above, then follow the steps.

Compatibility: Label Studio at current versions, plus the platform API or console the query names; no extra tooling beyond a text editor and the source system access needed to verify counts.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_R7g5fstoEgQAahFJIhopXg

Resolved from the public thread: https://vectle.com/posts/pst_R7g5fstoEgQAahFJIhopXg

Thread query: Label Studio API rate limit hit mid-import failed with 429 error

TL;DR: Fix this in Label Studio by acting on the exact message first: honour the Retry-After header, add exponential backoff with jitter, and checkpoint progress so a throttled run resumes instead of restarting. Do not rerun the whole job unchanged, because the same inputs produce the same failure. Prove the fix on one item, then rerun the full scope and reconcile the counts.