When performing an HTTP request in Node.js using the built-in fetch() (Node ≥18), the promise sometimes fails with: javascript Copy code TypeError: fetch failed [cause]: ConnectTimeoutError: Connect Timeout Error code: 'UND_ERR_CONNECT_TIMEO...

When rendering arrays, I see this console warning: pgsql Copy code Warning: Each child in a list should have a unique "key" prop. Without keys, my items sometimes reorder or behave unpredictably, especially when the array changes. How do I resolv...

My React component sets up event listeners or timers inside useEffect, but I never remove them. Over time, performance degrades—especially if components remount frequently. How should I fix this?

I fetch data inside a useEffect, but occasionally I see: vbnet Copy code Warning: Can't perform a React state update on an unmounted component. This is a no op, but it indicates a memory leak. This happens if the component unmounts before the fet...

My React app uses callbacks defined inline inside components. With many items or deep trees, the app slows dramatically, especially after several renders. For example, repeated rendering of a complex DisplayedGame component eventually hangs Chrome.

While fetching data in useEffect, I sometimes get this warning: "Can't perform a React state update on an unmounted component. This is a no op, but it indicates a memory leak..." I think it's due to calling setState after the component unmounted.

In my React component, I schedule state updates asynchronously (e.g. inside setTimeout or event handlers), but the updates refer to outdated state—leading to stale values and unexpected behavior. For example: js Copy code // count is always one le...

I store Blob objects in IndexedDB and later retrieve them. In Chrome and Edge, this works across tabs and refreshes—even when accessed via indexes. In Safari, they sometimes fail or come back empty, especially with getAll() after reopening. What's ca...

Reading a large file in chunks via FileReader.readAsArrayBuffer() in iOS Safari works for the first ~60 seconds, then fails with: nginx Copy code WebKitBlobResource error 1 This prevents continued processing of the file. It works fine in Chrome,...

My app stores Blobs (e.g., images) in IndexedDB. After closing Safari and reopening, retrieving the same entries via objectStore.index('idx').getAll(key) returns objects—but the Blob does not work when passed to URL.createObjectURL(blob), raising:

After editing a JavaScript or CSS file on the server (via SFTP), refreshing the browser sometimes causes that asset to fail with net::ERR_HTTP2_PROTOCOL_ERROR, even though opening the same file directly works.

Sending an AJAX request with a large JSON payload (e.g. >100 items) from the frontend, but the browser reports net::ERR_HTTP2_PROTOCOL_ERROR. Smaller payloads work fine. What gives?

Chrome console shows net::ERR_HTTP2_PROTOCOL_ERROR for JS or CSS files, even though the files exist and return HTTP 200 OK. Why does this happen and how can I fix it?

My application needs to spawn multiple processes (e.g. shell commands) concurrently, but performance degrades dramatically with many processes. Why is spawn() slow under heavy usage?

Occasionally my Node.js app crashes or behaves unpredictably without clear errors, especially during fs.readFile, Promises, or async calls. How should I handle errors more robustly?

Under load, my Node.js server slows down or becomes unresponsive. CPU usage spikes, and incoming requests lag or queue up. What’s causing this slow-down?

After running for a while, my Node.js process crashes with: pgsql Copy code FATAL ERROR: Reached heap limit Allocation failed – JavaScript heap out of memory What typically causes this, and how can I prevent it?

My Node.js code has multiple layers of nested callbacks, making it hard to read and maintain. Error handling is messy and debugging feels frustrating. How do I fix this?

When I use asyncio.create_task() or async generators, I often get silent bugs—tasks never run, exceptions go unnoticed, or cancellations don't behave as expected. Why does asyncio misbehave this way?

I run Python scripts using subprocess.Popen repeatedly in a loop. Over time, system memory increases, even after processes complete. The Python process itself doesn’t grow—but system memory remains tied up. What’s going wrong?