Guides
A useful place to start, with a route to the related result.
Guides 169–192 of 348
Troubleshooting guide
Before you skip or mark a flaky test, know what the marker hides
Compare skip, xfail, strict xfail and a separate quarantine suite so that taking a flaky test out of the way leaves a visible, dated record instead of a permanent blind spot.
Troubleshooting guide
MySQL to PostgreSQL: the decisions a data copy does not make for you
Case-insensitive lookups, zero dates, tiny-integer flags, enums, auto-increment keys and views: what the documentation says changes, and which choices belong to you.
Troubleshooting guide
Webpack to Vite: translate the config item by item and treat environment variables as public
Inventory every loader, plugin and setting first, then handle environment variables, require calls and glob imports, and keep the type check that Vite does not run.
Troubleshooting guide
Adopt TypeScript one folder at a time: allowJs, checkJs and a strict area that only grows
How JavaScript and TypeScript coexist, how to find type errors before renaming files, and why strictness is a dial you raise folder by folder.
Troubleshooting guide
Replacing one jQuery or AngularJS feature: write its contract before you touch it
Where support stands for old jQuery and AngularJS, what a feature's hidden contract contains, and how to prove a replacement matches it without rewriting the page.
Troubleshooting guide
Which Node.js line should you move to? Read the project's schedule, then ask your host
Two clocks decide when a Node.js version stops being usable: the project's release schedule and your host's runtime list. How to read both and find every place the version is set.
Troubleshooting guide
Native modules after a Node.js runtime change: what breaks, how to find it and what fixes it
Compiled Node.js add-ons depend on interfaces that stay stable across majors only if they use Node-API. How to find them, test them in a clean install and decide each one.
Troubleshooting guide
Express 4 to 5: test the behaviour changes, not just the methods you rename
The documented Express 5 changes that alter what a route matches, how async errors flow and what request properties contain, with a safe way to check them before upgrading.
Troubleshooting guide
Python 3.9 or 3.10 to 3.13: what was removed, and why compiled packages may not install
The standard-library modules removed in Python 3.12 and 3.13, how to find them in your code and dependencies, and how wheel tags and pinned requirements decide whether an install works.
Troubleshooting guide
Moving off Heroku: list the Procfile, release command, config names, add-ons and jobs first
What a Heroku app depends on outside its repository, how each item behaves according to Heroku's documentation, and how to list them without exposing a single secret.
Troubleshooting guide
Copying a Heroku Postgres database out: capture, download, rehearse the restore and reconcile
How Heroku's logical backups work, why a restore deletes the target first, the snags the documentation names, and what to compare before a final copy.
Troubleshooting guide
Upgrading Rails 7.x: take each minor version separately and read what changes
Why the Rails guide asks for one minor version at a time, what the guide lists for each 7.x step, and how framework-defaults files let you adopt changes gradually.
Troubleshooting guide
A Rails 6 app stuck before 7.0: run the Zeitwerk check and read what it reports
Zeitwerk autoloading is mandatory from Rails 7.0. How to check an app's file and constant names, what typical failures mean, and why eager loading is the real test.
Troubleshooting guide
Webpacker is retired: your Rails JavaScript options and what each means for an upgrade
What 'retired' means for a Rails app, the three successors its README names, and how to inventory what Webpacker does for you before choosing.
Troubleshooting guide
Changing a column on a large table: add, backfill, reconcile, switch, and only then drop
Why a single ALTER can lock or rewrite a big table, what the PostgreSQL and MySQL documentation say about each form, and how a stepwise change keeps a way back.
Troubleshooting guide
Reading vendor support dates: upstream, host, scheduled and final are different things
How Node.js, Python, Rails, Ruby, PostgreSQL and MySQL each publish support information, why the words differ, and what to record when you plan an upgrade around a date.
Troubleshooting guide
Before you change a version, record what your tests say today
A baseline run turns 'the upgrade broke it' into evidence. Three honest baseline states, what a green suite does not cover and what to do when there are no tests.
Troubleshooting guide
Can your sign-up or checkout flow be finished with a keyboard alone? A test script and the focus rules behind it
Keyboard operation, focus order, a visible focus indicator and focus not hidden by a sticky banner are four separate WCAG 2.2 checks. Run them on one flow before paying for an audit.
Troubleshooting guide
Form fields without labels and errors nobody hears: the three WCAG checks that fix most form failures
Visible labels, an error in text that names the field and a status message announced without moving focus. What each WCAG 2.2 criterion asks for and how to test it.
Troubleshooting guide
Sign-in fails with a redirect URI mismatch? Compare the two addresses character by character
A redirect mismatch is a string comparison that failed. Find the address your app really sends, compare it with the provider list and fix the right side.
Troubleshooting guide
Provider sign-in works but your app rejects the return? Check state, verifier and a callback handled twice
When the provider approves the user and your callback still fails, the missing piece is usually a stored state or verifier value, or a one-time code that was used twice.
Troubleshooting guide
Login succeeds then sends you back to the login page? Read the session cookie the browser actually keeps
A login loop usually means the browser refused or never returned the session cookie. Use this table of attributes to find which one without sharing a single cookie value.
Troubleshooting guide
Login works locally but loops behind a proxy or load balancer: the app may think it is on plain HTTP
A reverse proxy often ends HTTPS and passes plain HTTP to your app. If the app does not trust the forwarded protocol, secure cookies and callback addresses go wrong.
Troubleshooting guide
Slow Largest Contentful Paint? Split the delay into four parts before you change anything
Compressing images is the usual first move and often the wrong one. Find which of four parts of the load time is long, then fix that part.
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