Understand the idea

An unchanged page does not automatically mean a cache is at fault. The new source may never have been built, the wrong folder may have been uploaded, or a different rule may override the change.

Follow the change through three checkpoints: the source file, the generated upload file and the response the browser actually receives. If the new value is missing from the generated file, start with the build. If it is in the response but not visible, inspect the rendering rules.

Read the example

Two fictional evidence chains. They illustrate different causes of a similar visible symptom.

Diagnostic notes · EXAMPLE
Source: orange
Generated output: violet
Received CSS: violet
First repair: rebuild the output

Source: orange
Generated output: orange
Received CSS: orange, but result is violet
Next check: the winning CSS declaration

More than one cache can exist

A browser and a shared hosting cache can hold separate copies. A browser reload does not necessarily refresh every upstream cache. Developer tools often offer a temporary browser-cache bypass while open; read the tool’s label and scope. A fresh browser request can still receive a response from an intermediary.

Interpret responses carefully

A 304 response means a stored representation can be reused after validation; it is not a missing-file error. A 200 response alone does not prove that the file contains your newest edit. Inspect the response body and relevant headers together.

Cache-Control: no-cache permits storage but requires validation before reuse. no-store asks caches not to store the response. Neither is a promise to erase browser history or downloaded files. This site uses no-store; these lessons also explain other sites you may maintain.

Change one thing at a time

Record the deployment and resource URL you are checking. Avoid changing DNS, filenames and cache settings together when only one value is wrong. With immutable versioned assets, a new filename can identify a new build; that is a design choice rather than a substitute for a correct upload.

Trace the stubborn colour.

Continue the diagnostic toolkit

All six lessons and three cases · Next: A missing page needs the right response

A small mistake, explained

What goes wrong

You repeatedly clear caches while uploading an old build. The browser correctly receives the old file again.

How to fix it. Build the intended source and inspect the exact output before upload. Then verify the deployed URL, response body and active CSS rule. Investigate caching when the evidence points there.

Try it yourself

Follow the old-colour case. For each step, name one fact you know and one explanation that remains unproven.

Further reading

MDN: HTTP caching (new tab)

Original explanation and example prepared for HTML code FYI with AI assistance. Test the code in your own context. How these guides are made.