alibaba/nacos · error · FileNotFoundException

{getDescription()} cannot be resolved in the file system for

Error message

{getDescription()} cannot be resolved in the file system for checking its last-modified timestamp

What it means

Thrown by AbstractFileResolvingResource.lastModified() in its fallback path: when fileCheck is true, the URL connection reports lastModified 0 and content length <= 0, meaning neither the file system nor the URL connection could find the resource. FileNotFoundException indicates the resource is effectively missing on both fronts.

Source

Thrown at common/src/main/java/com/alibaba/nacos/common/packagescan/resource/AbstractFileResolvingResource.java:267

        if (ResourceUtils.isFileUrl(url) || ResourceUtils.isJarUrl(url)) {
            // Proceed with file system resolution
            fileCheck = true;
            try {
                File fileToCheck = getFileForLastModifiedCheck();
                long lastModified = fileToCheck.lastModified();
                if (lastModified > 0L || fileToCheck.exists()) {
                    return lastModified;
                }
            } catch (FileNotFoundException ex) {
                // Defensively fall back to URL connection check instead
            }
        }
        // Try a URL connection last-modified header
        URLConnection con = url.openConnection();
        customizeConnection(con);
        long lastModified = con.getLastModified();
        if (fileCheck && lastModified == 0 && con.getContentLengthLong() <= 0) {
            throw new FileNotFoundException(getDescription()
                    + " cannot be resolved in the file system for checking its last-modified timestamp");
        }
        return lastModified;
    }

    /**
     * Customize the given {@link URLConnection}, obtained in the course of an
     * {@link #exists()}, {@link #contentLength()} or {@link #lastModified()} call.
     * Calls {@link ResourceUtils#useCachesIfNecessary(URLConnection)} and
     * delegates to {@link #customizeConnection(HttpURLConnection)} if possible.
     * Can be overridden in subclasses.
     *
     * @param con the URLConnection to customize
     * @throws IOException if thrown from URLConnection methods
     */
    protected void customizeConnection(URLConnection con) throws IOException {
        ResourceUtils.useCachesIfNecessary(con);
        if (con instanceof HttpURLConnection) {

View on GitHub (pinned to 9b989acdf1)

Solutions

1. Check resource.exists() before relying on lastModified().
2. Refresh/resolve the resource handle anew before each timestamp check rather than caching it.
3. Handle FileNotFoundException around lastModified() and treat it as 'resource removed'.
4. For watch loops, recreate the Resource from the current path on each cycle.

Example fix

// before
long ts = resource.lastModified(); // throws when both file & URLConnection empty

// after
long ts;
try {
    ts = resource.lastModified();
} catch (FileNotFoundException e) {
    ts = -1L; // treat as missing
}

if (!resource.exists()) {
    return -1L; // treat as missing
}
return resource.lastModified();

boolean hasLastModified(Resource r) {
    try { return r.exists() && r.lastModified() > 0L; }
    catch (IOException e) { return false; }
}

try {
    long ts = resource.lastModified();
} catch (FileNotFoundException e) {
    log.debug("Resource gone for lastModified: {}", e.getMessage());
    ts = -1L;
}

When it happens

Trigger: Calling resource.lastModified() (often transitively via resource.exists() or freshness checks) where the resource is a missing file-backed URL and the URLConnection also yields no last-modified/length; scanning deleted classpath roots.

Common situations: Deleted/rotated log or config file whose resource handle is still cached; hot-reload watching a file that was removed; URLConnection to a removed remote resource returning empty headers; stale resource reference after redeploy.

Related errors

• {getDescription()} cannot be resolved in the file system for
• {getDescription()} cannot be resolved to absolute file path
• {getDescription()} cannot be resolved in the file system for
• Cannot create a relative resource for {getDescription()}
• {getDescription()} cannot be opened because it does not exis

AI-assisted analysis of alibaba/nacos@9b989acdf1 (2026-08-14). Data as JSON: /api/errors/6a00a2e5be376cad. Report an issue: GitHub.