What causes " " in Tencent/matrix?

Inspect TaskExecuteException.getCause() for the real failure

Tencent/matrix · error · TaskExecuteException

<e.getMessage()>

Error message

<e.getMessage()>

What it means

UnusedResourcesTask.call() wraps any Exception thrown while computing unused resources into a TaskExecuteException with e.getMessage() as the message and the original as cause. Like UnusedAssetsTask, it is a generic wrapper; the actionable info is in the cause.

Solutions

Inspect TaskExecuteException.getCause() for the real failure
Validate R.txt and mapping files are readable and well-formed before the task
If the cause is 'Found resource cycle!', break the cycle or ignore those resources
Re-extract the APK and re-run to rule out corrupted input

Example fix

// before
throw new TaskExecuteException(e.getMessage(), e);
// after
throw new TaskExecuteException("UnusedResourcesTask failed: " + e, e);

Defensive patterns

Strategy: try-catch

Validate before calling

File rTxt = new File(params.get(JobConstants.PARAM_R_TXT));
File dir = new File(config.getUnzipPath());
if (!rTxt.isFile() || !dir.isDirectory()) throw new IllegalStateException("invalid inputs for unused-resources task");

Try / catch

try {
    TaskResult r = task.call();
} catch (TaskExecuteException e) {
    Throwable cause = e.getCause();
    log.error("unused-resources failed", cause != null ? cause : e);
}

Prevention

Always log getCause(), the wrapper message can be null or unhelpful
Pre-validate R.txt, mapping, and unzip directory before the job
Re-extract the APK if inputs may be stale or corrupted

When it happens

Trigger: Any exception during call(): file IO while scanning res/ directories, parsing R.txt/mapping files, JSON result building, or the resource-cycle IllegalStateException from readChildReference().

Common situations: Missing/odd res directory contents, malformed R.txt or mapping files, cyclic resources, or unreadable files in the extracted APK on CI.

Understand the failure class

Background: "failed to read file", EACCES, ENOENT and "could not read <path>" errors: when a program can't read a file from disk — this error's family across 49 libraries.

Related errors

AI-assisted analysis of Tencent/matrix@3b8293bd65 (2026-09-08). Data as JSON: /api/errors/2404ca5bf23f0d11. Report an issue: GitHub.

Appendix: source

Thrown at matrix/matrix-android/matrix-apk-canary/src/main/java/com/tencent/matrix/apk/model/task/UnusedResourcesTask.java:498

            unusedResSet.addAll(resourceDefMap.values());
            Log.i(TAG, "find resource declarations %d items.", unusedResSet.size());
            decodeCode();
            Log.i(TAG, "find resource references in classes: %d items.", resourceRefSet.size());
            decodeResources();
            Log.i(TAG, "find resource references %d items.", resourceRefSet.size());
            unusedResSet.removeAll(resourceRefSet);
            Log.i(TAG, "find unused references %d items", unusedResSet.size());
            Log.d(TAG, "find unused references %s", unusedResSet.toString());
            JsonArray jsonArray = new JsonArray();
            for (String name : unusedResSet) {
                jsonArray.add(name);
            }
            ((TaskJsonResult) taskResult).add("unused-resources", jsonArray);
            taskResult.setStartTime(startTime);
            taskResult.setEndTime(System.currentTimeMillis());
            return taskResult;
        } catch (Exception e) {
            throw new TaskExecuteException(e.getMessage(), e);
        }
    }
}

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