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Showing entries 561–600 of 651 in this first collection.
Troubleshooting guide
Bounced, blocked or dropped: what SendGrid's event feed tells your app to do
Separate permanent bounces, temporary blocks and drops caused by suppression, and store each once so your app stops mailing addresses that cannot receive.
Troubleshooting guide
Verifying SendGrid's signed event webhook: why the raw body matters
How SendGrid signs its event feed, why re-serialised JSON breaks verification, and how to test that a forged event flags nobody.
Troubleshooting guide
Twilio says sent, then delivered, then sent again: store a final state, not the latest arrival
Rank Twilio message statuses so an out-of-order callback never overwrites a final result, and keep error codes as information rather than rules.
Troubleshooting guide
Twilio callback checks fail or never fire: the exact URL and what test credentials cannot do
Why Twilio's request signature depends on the exact URL it called, and why test credentials cannot show delivery callbacks at all.
Troubleshooting guide
Alerting Slack from your app: webhook or bot token, and how to avoid slowing or flooding it
Choose between an incoming webhook and a bot token, keep alerts outside the customer's request, and respect Slack's per-channel rate limit and Retry-After.
Troubleshooting guide
Slack events hit your endpoint twice, or not at all: signature, timestamp and the three-second rule
How Slack signs events, why the raw body and a five-minute window matter, and how to reply in time without running the work twice.
Platform
SendGrid in your app: authenticated sending, then what the delivery events tell you
Understand what SendGrid's domain authentication proves, what its event feed reports and which parts of a transactional email connection are yours to build and test.
Platform
Twilio SMS in your app: sending is one call, knowing what happened is the work
Understand message statuses, out-of-order delivery callbacks, request signatures and sender registration before connecting an app to Twilio messaging.
Platform
Slack API in your app: posting alerts and receiving events are two different jobs
Understand when to use an incoming webhook or a bot token, how Slack rate limits posts, and the signing, timing and retry rules for events it sends to your app.
Troubleshooting guide
Direct uploads with signed storage links: what the link allows, how long it lasts and what it does not check
A signed upload link is a bearer token tied to the credentials that made it; design the key, lifetime, after-upload checks and the cleanup of uploads nobody confirms around that, and note where S3-compatible stores differ.
Troubleshooting guide
Rate limited or timing out: wait as the provider asks, then back off with spread
Read Retry-After in both of its forms, add capped exponential backoff with randomness, bound the attempts and total time, and test the policy with a scripted fake provider.
Troubleshooting guide
A timed-out create may have worked: making retried writes safe
Three ways to avoid duplicate records when retrying a create, from provider idempotency keys to lookup and an attempt ledger, and what to do when none is possible.
Troubleshooting guide
Website form to Pipedrive: store first, match by email, create a linked lead, respect the limits
The order of calls, the API versions, the matching rule, the rate limits and the outage design for pushing a form enquiry into Pipedrive without losing it, and the lookup that keeps a lost reply from creating a second lead.
Troubleshooting guide
Keep a register of your integrations: what expires, what limits you and what gets retired
A one-page register of each outside service's credentials, owners, dates and limits, with documented examples of what ends and where to watch for notices.
Troubleshooting guide
Certbot renewal on your own server: dry run, schedule, reload hook and the old 30-day rule
How to check that Let's Encrypt renewal will work before the certificate expires, what actually schedules it, why the web server must reload, and why the renewal threshold changed.
Troubleshooting guide
Certificate validation fails: port 80, redirects, DNS challenges and rate limits
What the HTTP-01 challenge needs from your server, when the DNS-01 challenge is the right choice, and how failed attempts can lock you out for an hour or a week.
Troubleshooting guide
Kubernetes pod will not start: CrashLoopBackOff and ImagePullBackOff are different problems
How to read container state, previous logs and events to tell a crashing container from an image that cannot be pulled, and which manifest or values change fits each.
Troubleshooting guide
Pods Running but not Ready, and rollouts that never finish: probes and the progress deadline
What liveness, readiness and startup probes each do, why a liveness probe can cause an outage, how a Deployment reports a stalled rollout, and how to roll back safely.
Platform
Kubernetes: find out whether the manifest, the image or the cluster is at fault
How to separate a Deployment problem you can fix in a manifest or Helm values from application bugs and cluster faults, and how a one-Deployment repair is accepted.
Troubleshooting guide
Moving a PostgreSQL database to a new server: dump, roles, restore and the cutover freeze
What pg_dump does and does not include, how to rehearse a restore, how roles and ownership affect it, and why writes must stop before the final dump.
Troubleshooting guide
Reading a cloud bill: where the money usually hides and what to check before deleting
A first pass through a cloud bill: group by service and usage type, compare months, look for idle volumes and addresses, and check use and back up before any removal.
Buyer collection
For a founder with one server and nobody who looks after it
Which fixed infrastructure jobs fit a founder running a VPS alone, in what order to consider them, and what you must hold yourself.
Collection
Bringing a server into good order: the sequence that avoids locking yourself out
An ordered path for a VPS that works but is not looked after: a way back, access and firewall, updates, a proper home for the app, logs, secrets and certificates, with the check that closes each step.
Troubleshooting guide
Your container port is open to the internet even though ufw says it is closed
How Docker-published ports sit outside the rules ufw manages, how to bind a port to the loopback address, and how to prove from outside which ports a server really exposes.
Troubleshooting guide
Turn off SSH passwords without locking yourself out: order, files and checks
The safe order for key-only SSH and a deny-by-default firewall, why the first value wins in sshd_config, how to read the effective settings, and what to keep open while you test.
Inspectable example
Worked example: a synthetic Linux baseline verification sheet
A labelled synthetic sheet of the checks that prove key-only SSH, a deny-by-default firewall and automatic security updates, with the pass and fail reading for each row.
Troubleshooting guide
nginx sends the wrong path upstream: proxy_pass URIs and location matching
Why one route returns 404 or the wrong page behind nginx: how a location is chosen, what proxy_pass does when it has a URI, and the cases where nginx cannot substitute the path.
Troubleshooting guide
nginx timeouts, retries and WebSockets: what the defaults do to slow requests
How proxy timeouts, upstream failure counting and retry settings interact, why a WebSocket drops after a minute of silence, and which change is safe for a slow endpoint.
Platform
nginx: separate the proxy, the application and the network before you change a setting
What nginx can fix for a site behind it, what only the application or the network can, and how a proxy repair is accepted: reproduce, test the configuration, reload, prove.
Troubleshooting guide
Members-only pages on Wix, Squarespace and Webflow: what each builder's own tools can and cannot do
Wix and Squarespace each have a built-in members feature with different rules. Webflow no longer has one. This guide sets out how each works and the limits worth knowing before you promise anyone privacy.
Troubleshooting guide
Bubble apps showing the wrong records: why hiding on the page is not protection
In Bubble, data reaches the browser unless a privacy rule on the data type stops it. This guide explains the rule settings that surprise people, the one-step limit on relationships and a safe two-account test.
Troubleshooting guide
Leaving Wix or Squarespace: what each builder will export and what you must rebuild
Neither builder gives a full export. This guide lists what each one will and will not let out, how the WordPress importer treats it, and why a move should start from a page list, not a file.
Troubleshooting guide
301 redirects on Webflow, Squarespace and Wix: what each tool accepts and how to test the whole list
A redirect map is only as good as the tool that loads it. This guide covers each builder's rules and limits, the mistakes that overwrite or loop, and how to test every old address.
Troubleshooting guide
Webflow form emails not arriving: find the stage that failed before changing anything
A Webflow form is stored first and emailed second. A labelled test on the published site shows which stage fails, and each stage has its own short list of causes.
Troubleshooting guide
Wix form notifications: the automation behind the email and why its recipient goes stale
Wix emails form submissions through an automation. The recipient list lives there, not in the form, so changing an account email or a collaborator does not change who gets the message.
Troubleshooting guide
Analytics counting every visit twice on a site builder: one tag, one route, one check
Double counting on Webflow, Squarespace and Wix usually comes from installing the same tag through the builder's integration and by pasting code. This guide shows how to find it.
Troubleshooting guide
A slow landing page on Webflow, Squarespace or Wix: what you can change and what you cannot
On a hosted builder you cannot tune the server, only what you put on the page. This guide ranks the usual weight sources, gives each builder's documented limits and says how to measure honestly.
Inspectable example
Synthetic redirect map: twelve old addresses, four traps and the result each row must give
An invented twelve-row sheet for a pretend small business shows how a redirect map is written and tested, including a chain, a query address, an image and pages with no new home.
Inspectable example
Synthetic form delivery test log: stored but never emailed, then fixed and re-tested
An invented test log shows how three labelled submissions locate a stale recipient on a builder form and prove the fix, stage by stage.
Inspectable example
Synthetic Bubble privacy test: four personas, five records and the counts each must see
An invented matrix for a pretend Notes data type shows the counts four personas see before and after a privacy rule, and the checks that prove the rule.