Troubleshooting uploads

Upload problems fall into three buckets: the file was rejected before upload, the transfer itself failed, or the dataset was created but something after it hiccuped. Find your symptom below.

"Unsupported file type. Upload one of: .csv, .json, .parquet, .xlsx"#

Only those four extensions are accepted. The content usually converts losslessly:

• .tsv / .txt — save as CSV.
• .jsonl / .ndjson — rename to .json; newline-delimited JSON is detected automatically.
• .xls — save as .xlsx in Excel.

The Excel file uploads but looks empty or wrong#

Only the workbook's first sheet is imported. Move the data to the first sheet, or export the sheet you want as its own file. A related message — "Excel file appears to be empty or contains no data." — usually means the first sheet is blank.

Very large workbooks hit a browser limit: "Excel files over 250 MB can't be validated in the browser. Convert this to CSV or Parquet for large datasets."

The manifest says "Can't read this"#

Browser-side validation couldn't parse the file (you'll see a specific reason like "No columns found in this CSV file."). Check that the file opens cleanly in another tool, that the extension matches the content, and that CSVs have a header row. Retry re-validates in place after you fix the file.

If instead you see "File validation is unavailable", the browser validator itself couldn't start — you can still create the dataset, and the server validates during ingestion (its verdict is authoritative).

"Upload stalled — no data transferred"#

The transfer to storage stopped (the default watchdog trips after 3 minutes without bytes). Usually connectivity: check your network, pause a VPN if you're on one, and retry. If it reproduces reliably on a self-hosted deployment, the storage endpoint or its CORS configuration is the usual suspect — loop in your administrator.

The file is rejected as too large#

The per-file cap is shown in the dropzone hint. Two levers: export a smaller slice, or convert to Parquet (columnar compression routinely shrinks a CSV several-fold and validates faster). In cleaning-enabled projects the cap is a fixed 800 MB — upload into a non-cleaning project if the file is bigger.

A column name is flagged in AI Readiness#

Column names must be snake_case — lowercase, no leading digit, no special characters — so SQL and the AI work reliably. Use the wizard's auto-fix, or edit the name in place. You can't continue while a name is invalid.

"Dataset Creation Failed" after the upload finished#

The server couldn't ingest the file. The screen shows the server's reason — a parse error deep in the file is the common one (browser validation reads only the head; the server reads everything). Try Again retries the same file; Start Over resets the wizard. If the message names a format problem, re-export the file and check for corruption.

"…search indexing failed. 'Chat with dataset' won't work until it's re-indexed."#

The dataset was created fine — only the semantic index behind chat didn't build. Select Re-index right on the warning, or later under Settings → Maintenance. Queries, previews, and dashboards work regardless.

Rows were skipped during cleaning validation#

In cleaning-enabled projects, the deep scan may report "N row(s) with type mismatches will be excluded" — rows whose values can't be coerced to the detected column types. Continue to create the dataset from the valid rows, or go back and fix the source data if those rows matter. See Data cleaning.

Still stuck?#

Re-run the upload in Manual mode (it surfaces each stage's result), try a small sample of the same file to isolate whether size or content is the trigger, and note the exact error text before contacting your administrator or support.