## TL;DR
Tesseract's 'failed loading language eng' means the English traineddata file is missing from the tessdata directory it actually reads, which is often not the one you expect. Point TESSDATA_PREFIX at the directory containing eng.traineddata, or install the tesseract-ocr-eng package, and the scanned annual report will OCR.

## The error
```text
Error opening data file /usr/share/tesseract-ocr/5/tessdata/eng.traineddata
Please make sure the TESSDATA_PREFIX environment variable is set to your "tessdata" directory.
Failed loading language 'eng'
Tesseract couldn't load any languages!
```

## Fix it
1. Find where eng.traineddata actually lives on the system with a filesystem search, for example find / -name 'eng.traineddata'.
   Expected: Expected: the search returns a real path, possibly under a versioned directory you did not expect.
2. Set TESSDATA_PREFIX to the parent tessdata directory in the pipeline environment and retry the OCR call.
   Expected: Expected: tesseract --list-langs shows eng and the OCR run starts.
3. If no eng.traineddata exists anywhere, install the language data package for your distro (tesseract-ocr-eng on Debian/Ubuntu) or download eng.traineddata into a tessdata dir you control.
   Expected: Expected: the traineddata file exists and TESSDATA_PREFIX points at it.
4. Verify on a single scanned page before running the full annual report, and log the TESSDATA_PREFIX value at pipeline startup.
   Expected: Expected: one page OCRs cleanly and the config is visible in logs for the next debug session.

## When to use
- Your scanned-annual-report OCR fails before reading a single page with the language error.
- You need to locate the real tessdata directory versus the assumed one.
- You deploy OCR in containers where language packs are often omitted.

## When not to use
- Tesseract loads eng but produces garbage - that is image quality or preprocessing, not this error.
- The error names a different language like 'fra' - install that language pack instead.
- You use a cloud OCR API - then Tesseract is not in the loop at all.

## Why it happens
Tesseract separates the engine binary from its language data. Package installs sometimes put traineddata in a versioned path (/usr/share/tesseract-ocr/5/tessdata) while the binary looks elsewhere, or minimal images ship the binary without any language packs. The error names the exact path it tried, which is the fastest clue.

## Variant phrasings
### tesseract failed loading language eng
Same failure and fix; some searchers phrase the query this way.
### tesseract couldn't load any languages fix
Same failure and fix; some searchers phrase the query this way.

## Edge cases
- Setting TESSDATA_PREFIX to the tessdata dir itself (not its parent) is the classic misconfiguration.
- Some builds embed a default tessdata path at compile time that ignores the environment variable until you pass --tessdata-dir.

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_zajYKPvfRmA8ahDwJocQSQ