What causes "An error occurred processing file %s. Error: %s" in nodejs/node?

Pass the correct source encoding explicitly: `genrb --encoding UTF-8 root.txt`.

An error occurred processing file %s. Error: %s

Error message

An error occurred processing file %s. Error: %s

What it means

The catch-all processing error in processFile(): ucbuf_open returned a non-null UCharacterStream but the status is a failure (not U_FILE_ACCESS_ERROR, which is handled separately by error 778), or the stream is null with a non-file-access error. The message includes the resolved filename and the ICU error name, covering encoding problems, BOM issues, malformed input, and stream construction failures.

Source

Thrown at deps/icu-small/source/tools/genrb/genrb.cpp:667

        } else {
            openFileName.append(inputDir, status);
        }
    }
    openFileName.appendPathPart(filename, status);

    // Test for CharString failure
    if (U_FAILURE(status)) {
        return;
    }

    ucbuf.adoptInstead(ucbuf_open(openFileName.data(), &cp,getShowWarning(),true, &status));
    if(status == U_FILE_ACCESS_ERROR) {

        fprintf(stderr, "couldn't open file %s\n", openFileName.data());
        return;
    }
    if (ucbuf.isNull() || U_FAILURE(status)) {
        fprintf(stderr, "An error occurred processing file %s. Error: %s\n",
                openFileName.data(), u_errorName(status));
        return;
    }
    /* auto detected popular encodings? */
    if (cp!=nullptr && isVerbose()) {
        printf("autodetected encoding %s\n", cp);
    }
    /* Parse the data into an SRBRoot */
    data.adoptInstead(parse(ucbuf.getAlias(), inputDir, outputDir, filename,
            !omitBinaryCollation, options[NO_COLLATION_RULES].doesOccur, options[ICU4X_MODE].doesOccur, &status));

    if (data.isNull() || U_FAILURE(status)) {
        fprintf(stderr, "couldn't parse the file %s. Error:%s\n", filename, u_errorName(status));
        return;
    }

    // Run filtering before writing pool bundle
    if (filterDir != nullptr) {

View on GitHub (pinned to 1b2de5e052)

Solutions

Pass the correct source encoding explicitly: `genrb --encoding UTF-8 root.txt`.
Re-save the offending .txt as UTF-8 (with or without BOM per ICU's expectations) using a reliable editor.
Read the printed u_errorName (e.g. U_UNSUPPORTED_ERROR, U_INVALID_CHAR_FOUND) to pinpoint encoding vs. parse causes.
If the file is generated upstream, fix the generator rather than papering over the encoding.

Example fix

// before
genrb root.txt            # ambiguous encoding
// after
genrb --encoding UTF-8 root.txt

Defensive patterns

Strategy: validation

Validate before calling

# Preflight: confirm each source file is valid UTF-8 (or matches --encoding)
enc="${ENCODING:-UTF-8}"
for f in "$@"; do
  if [ "$enc" = "UTF-8" ] && command -v iconv >/dev/null 2>&1; then
    iconv -f UTF-8 -t UTF-8 "$src_dir/$f" >/dev/null 2>&1 || {
      echo "ERROR: $f is not valid UTF-8" >&2; exit 2; }
  fi
done

Try / catch

genrb --encoding "$enc" -s "$src_dir" "$@" 2>err.log
if grep -q 'An error occurred processing file' err.log; then
  echo "Source processing error; see err.log for the u_errorName and offending file" >&2
  exit 1
fi

Prevention

Standardize all source .txt as UTF-8 with a BOM and pass --encoding UTF-8 explicitly.
Audit upstream generators that produce locale .txt to prevent encoding drift.

When it happens

Trigger: Source .txt in an encoding genrb cannot auto-detect and that conflicts with --encoding; missing or malformed BOM; binary garbage in a .txt; truncated UTF-8 sequences. Any UErrorCode other than U_FILE_ACCESS_ERROR coming out of ucbuf_open lands here.

Common situations: Mixing source encodings without specifying --encoding; files saved as UTF-16 without BOM; copy-pasting locale data through tools that mangle bytes; CRLF or non-character codepoints that the detector rejects.

Related errors

AI-assisted analysis of nodejs/node@1b2de5e052 (2026-08-13). Data as JSON: /api/errors/2dc9ce87cad5758a. Report an issue: GitHub.