nodejs/node · error

U_INVALID_CHAR_FOUND

U_INVALID_CHAR_FOUND

Error message

icupkg/ures_enumDependencies(%s res=%08x) alias string contains non-invariant characters\n

What it means

checkAlias validates that a resource-bundle alias string uses only invariant characters; if uprv_isInvariantUString fails it prints the item name + resource handle and sets *pErrorCode = U_INVALID_CHAR_FOUND (returns, does not exit). Alias strings must be invariant so they can be safely byte-swapped and matched.

Source

Thrown at deps/icu-small/source/tools/toolutil/pkgitems.cpp:229

    }
    checkIDSuffix(itemName, parent, parentLength, suffix, check, context, pErrorCode);
}

// get dependencies from resource bundles ---------------------------------- ***

static const char16_t SLASH=0x2f;

/*
 * Check for the alias from the string or alias resource res.
 */
static void
checkAlias(const char *itemName,
           Resource res, const char16_t *alias, int32_t length, UBool useResSuffix,
           CheckDependency check, void *context, UErrorCode *pErrorCode) {
    int32_t i;

    if(!uprv_isInvariantUString(alias, length)) {
        fprintf(stderr, "icupkg/ures_enumDependencies(%s res=%08x) alias string contains non-invariant characters\n",
                        itemName, res);
        *pErrorCode=U_INVALID_CHAR_FOUND;
        return;
    }

    // extract the locale ID from alias strings like
    // locale_ID/key1/key2/key3
    // locale_ID

    // search for the first slash
    for(i=0; i<length && alias[i]!=SLASH; ++i) {}

    if(res_getPublicType(res)==URES_ALIAS) {
        // ignore aliases with an initial slash:
        // /ICUDATA/... and /pkgname/... go to a different package
        // /LOCALE/... are for dynamic sideways fallbacks and don't go to a fixed bundle
        if(i==0) {
            return; // initial slash ('/')

View on GitHub (pinned to 1b2de5e052)

Solutions

1. Regenerate the offending .res from the source locale XML/txt with current genrb.
2. Audit aliases for non-invariant characters: any byte > 0x7F or control char in an alias is invalid.
3. Do not hand-edit compiled .res files; edit source and recompile.
4. Run the ICU data build cleanly from a trusted source tree.

Example fix

# before: alias contains a non-invariant char (e.g. a raw UTF-8 byte)
# in source locale data the alias was edited to include non-ASCII
genrb bad.txt   # produces a .res with a non-invariant alias
# after: fix the alias in source to use only invariant (ASCII) characters
genrb fixed.txt

// C++: validate alias bytes are invariant before relying on them
#include "unicode/utypes.h"
bool aliasIsSafe(const char16_t *alias, int32_t len) {
    return uprv_isInvariantUString(alias, len);  // false => would trigger U_INVALID_CHAR_FOUND
}

// narrows an alias to 'safe to swap/match' before use
bool isInvariantAlias(const char16_t *alias, int32_t len) {
    return alias != nullptr && len >= 0 && uprv_isInvariantUString(alias, len);
}

// checkAlias sets *pErrorCode; caller must test it after enumerating deps
UErrorCode err = U_ZERO_ERROR;
ures_enumDependencies(..., &err);
if (err == U_INVALID_CHAR_FOUND) { /* a non-invariant alias was found; rebuild the .res */ }

When it happens

Trigger: A .res resource contains an alias with non-ASCII or otherwise non-invariant characters; a corrupt resource bundle where alias data is damaged. The guard is the first check in checkAlias.

Common situations: Hand-edited or corrupt locale resource data with bad alias entries; a .res produced by tooling that wrote non-invariant bytes into an alias; encoding corruption during transfer.

Related errors

• icupkg: udata_openSwapper(\"%s\") failed - %s\n
• U_MEMORY_ALLOCATION_ERROR
• U_BUFFER_OVERFLOW_ERROR
• missing list file\n
• U_MEMORY_ALLOCATION_ERROR

AI-assisted analysis of nodejs/node@1b2de5e052 (2026-08-13). Data as JSON: /api/errors/426269ad7cd21c54. Report an issue: GitHub.