karatelabs/karate · error · RuntimeException

temp file not found

Error message

temp file not found

What it means

DiskBackedList's DiskBackedIterator constructor wraps FileNotFoundException from opening the backing temp file in a RuntimeException reading 'temp file not found'. The iterator needs to reopen the temp file for sequential reading, and it is gone at iteration time.

Solutions

1. Check the chained FileNotFoundException for the missing path
2. Keep list lifetime short and iterate promptly after creation
3. Point java.io.tmpdir at an app-managed directory excluded from cleanup
4. Do not close/delete the backing file before all iterators are done

Example fix

// before
File f = File.createTempFile("kdbl", ".tmp", new File("/tmp/shared"));
// after
File f = File.createTempFile("kdbl", ".tmp", appManagedDir); // not auto-cleaned

File f = backingFileOf(list);
if (f == null || !f.exists()) throw new FileNotFoundException("backing temp file gone: " + f);

boolean tempFilePresent(DiskBackedList l, File f) { return f != null && f.exists(); }

try { for (Object o : list) process(o); } catch (RuntimeException e) { if ("temp file not found".equals(e.getMessage())) { log.error("backing temp file was deleted; recreate the list", e.getCause()); } throw e; }

When it happens

Trigger: The temp file was deleted between list creation and iterator construction (external cleanup, same-process delete, container tmp reaping); close() deleted the file and an old iterator is reused; temp directory recreated/cleared.

Common situations: Long-running jobs iterating lazily long after list creation; /tmp cleaners (systemd-tmpfiles) deleting files; multiple lists sharing a directory that gets wiped.

Understand the failure class

Background: "File not found" and ENOENT errors: why libraries can't find a file that should exist — this error's family across 50 libraries.

Related errors

• failed to read next line
• failed to read item at index
• boot.read: file not found
• boot.read: file not found
• Failed to read bytes from

AI-assisted analysis of karatelabs/karate@a22eb90246 (2026-09-12). Data as JSON: /api/errors/bb5924e1c6255707. Report an issue: GitHub.

Appendix: source

Thrown at karate-core/src/main/java/io/karatelabs/match/DiskBackedList.java:237

        if (tempFile.exists()) {
            if (!tempFile.delete()) {
                logger.warn("failed to delete temp file: {}", tempFile);
            }
        }
    }

    private class DiskBackedIterator implements Iterator<Object> {
        private final BufferedReader reader;
        private int currentIndex = 0;
        private String nextLine = null;
        private boolean hasNextCalled = false;

        DiskBackedIterator() {
            try {
                reader = new BufferedReader(
                        new InputStreamReader(new FileInputStream(tempFile), StandardCharsets.UTF_8));
            } catch (FileNotFoundException e) {
                throw new RuntimeException("temp file not found", e);
            }
        }

        @Override
        public boolean hasNext() {
            if (hasNextCalled) {
                return nextLine != null;
            }
            hasNextCalled = true;
            if (currentIndex >= size) {
                closeReader();
                return false;
            }
            try {
                nextLine = reader.readLine();
                if (nextLine == null) {
                    closeReader();
                    return false;

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