When an upload says unsupported file type, invalid format, or import failed, do not fix it by renaming the suffix alone. Check the real file header, extension meaning, and size limit first, then inspect text encoding, CSV delimiter/header/column shape, and whether JSONL contains one valid JSON value per line. Re-export, convert, or compress only after the root mismatch is clear. Chakan runs these checks locally in the browser and does not upload user files, scan for malware, or decide whether a platform should approve the file.
Upload / import format diagnostics
Upload file format error, import failed, and unsupported file type troubleshooting
A local workflow for unsupported file type errors, CSV import failures, JSONL line errors, text encoding problems, extension allow-lists, and upload size limits.
unsupported file typeinvalid file format troubleshootingupload file type not allowedCSV import failedJSONL line errorfix file encoding mojibakeupload size limit converterfile extension not supported
Separate single-file limits from total attachment limits
Many admin systems, inboxes, and support portals apply both a per-file limit and a total upload limit. An 18 MB PDF may fit under a 25 MB single-file rule, while two such files can fail as one attachment batch. Normalize MB, MiB, GB, and GiB first, then compare both the single file and the total batch before choosing compression, splitting, a download link, or a staged import.
- Confirm whether the platform uses MB or MiB before comparing limits.
- A file can fit individually while the full attachment batch still exceeds the cap.
- Public examples should use synthetic sizes only, not real filenames, attachment content, or import logs.
WebUploader scanner noise, PDF upload limits, noindex, and stale sitemap checks
404s for `/webuploader/`, `/Public/webuploader/`, or old plugin paths in access logs are usually scanner probes, not evidence that Chakan ships that uploader or that a real upload workflow is broken. Separate scanner noise from human upload issues first, then verify sitemap inclusion, fresh lastmod, self canonical, and no noindex before deciding whether to resubmit the topic for Baidu, 360, Sogou, or Shenma review.
- Must Do: Treat WebUploader 404 probes as scanner noise instead of creating fake files or fake upload routes.
- Must Do: Use public topic URLs and synthetic result examples for PDF/upload indexing checks.
- Should Do: Sample robots-sitemap, canonical exclusion, and stale-sitemap signals before each submission batch.
Common lookup scenarios
Troubleshoot unsupported file type or invalid file format messages
Check CSV import failures caused by delimiter, header, column count, or mojibake
Find the JSONL line that is not valid JSON before dataset import
Confirm extension, real type, and size before uploading images, PDFs, ZIPs, or attachments
Review exports from spreadsheets, databases, BI tools, AI datasets, or ecommerce admin panels
Share a repeatable pre-upload checklist with teammates
Recommended workflow
- Use file signature viewer to compare the header, browser MIME, and extension
- Use file extension lookup to understand whether the suffix matches the platform allow-list
- Convert MB, MiB, GB, and GiB before deciding whether compression or splitting is needed
- For text files, check UTF-8, UTF-8 BOM, GB18030, Big5, Shift_JIS, EUC-KR, or Windows-1252 before re-exporting
- Preview CSV delimiters, headers, empty columns, row counts, and column consistency before import
- Validate JSONL line by line and convert to a JSON array only after errors are fixed; never expose real file content, import logs, or customer data as public result URLs, sitemap entries, or llms.txt examples
Related tool entries
A local workflow for unsupported file type errors, CSV import failures, JSONL line errors, text encoding problems, extension allow-lists, and upload size limits.
File signature viewer
Inspect a local file header signature, browser MIME type, extension, and likely real file type without uploading the file.
LookupToolChakanFile extension lookup
Look up common file extensions, MIME types, format purpose, text/binary nature, related extensions, and handling tips.
LookupToolChakanFile size converter
Convert file sizes across SI and IEC units and compare decimal vs binary display values.
LookupToolChakanFile encoding viewer and converter
Inspect and convert local text file encodings such as UTF-8, UTF-16, GB18030, Big5, Shift_JIS, EUC-KR, and Windows-1252.
LookupToolChakanCSV table viewer and validator
Preview CSV as a table and validate delimiter, headers, empty rows, duplicate headers, and uneven column counts in the browser.
LookupToolChakanCSV template validator
Compare CSV headers with an import template to find missing required headers, extra columns, duplicate headers, and uneven rows in the browser.
LookupToolChakanCSV and JSON converter
Convert CSV to JSON or JSON to CSV in the browser with delimiter detection, header handling, and preview rows for imports and docs.
LookupToolChakanJSONL and JSON converter
Convert JSON Lines to a JSON array or JSON arrays to JSONL in the browser, with per-line validation for logs, datasets, and batch APIs.
LookupToolChakanImage format converter
Convert images locally between PNG, JPEG, and WebP with quality controls and output preview.
LookupToolChakanZIP archive viewer
Inspect a local ZIP archive for file count, folder count, extension distribution, estimated original size, and entry list.
LookupToolChakanFAQ
When an upload says unsupported file type, invalid format, or import failed, do not fix it by renaming the suffix alone. Check the real file header, extension meaning, and size limit first, then inspect text encoding, CSV delimiter/header/column shape, and whether JSONL contains one valid JSON value per line. Re-export, convert, or compress only after the root mismatch is clear. Chakan runs these checks locally in the browser and does not upload user files, scan for malware, or decide whether a platform should approve the file.
Can I fix an unsupported file type by changing the extension?
Usually no. Renaming changes only the suffix. If the real header, encoding, delimiter, or platform allow-list does not match, the import can still fail.
Do these import troubleshooting tools upload my file?
No. Header checks, encoding preview, CSV preview, and JSONL validation are designed to run locally in the browser, and user file content does not become a public result URL.
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