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noob here. Creating a PWA React app using create-react-app and running into the CSP issue regarding default set to none and no img setting to override it.
Have searched for and tried many, many helpful answers for this exact problem but have not hit upon the one that will work for my app. Maybe I just need a second pair of eyes?

The error is:

Cannot GET /

The console tells me this:

Failed to load resource: the server responded with a status of 404 (Not Found) localhost/:1 Refused to load the image 'http://localhost:3002/favicon.ico' because it violates the following Content Security Policy directive: "default-src 'none'". Note that 'img-src' was not explicitly set, so 'default-src' is used as a fallback.

localhost/:1 Failed to load resource: the server responded with a status of 404 (Not Found)

Screenshot of server.js where I tried to implement express-csp-header:

server.js enter image description here

Screenshot of index.html to show the added images and that there is no meta tag for CSP: index.html

enter image description here

I have tried adding the tag as advised elsewhere. I tried every other suggestion from stackoverflow that I could find. Please advise.

----EDIT--- I guess what I need to know is how to override the CSP that comes with webpack as part of Create-React-App because the console error message says that 'img src' is NOT defined so it defaulted to "default src", which is set to 'none'. I believed I have installed express-csp-header correctly and have 'img src' set correctly, why doesn't the browser find that?

----Another EDIT--- Here all this time I was thinking that webpack must be where the browser is getting the "default-scr: NONE" referred to in the error message. I just searched all of the files in react-script, which is where webpack config files live, and don't find any occurance of "default-scr: NONE". Is it an Express setting? Why am I dealing with CSP with this CRA app and not the other dozen I created the same way? Pulling my hair out.

Bruggineer
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1 Answers1

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Maybe I just need a second pair of eyes?

Yeah, it is difficult to find a black cat in a dark room, especially if it is not there.

Refused to load the image 'http://localhost:3002/favicon.ico' because it violates the following Content Security Policy directive: "default-src 'none'". Note that 'img-src' was not explicitly set, so 'default-src' is used as a fallback.

This is a great example of a misleading diagnostic message. Your issue have nothing to do with Content Security Policy (CSP).
Just place favicon.ico file into %PUBLIC_URL% folder and add into <head> section:

<link rel="icon" type="image/x-icon" href="%PUBLIC_URL%/favicon.ico">

All nitty-gritty is here. Briefly - browser by default tries to get favicon from the root of website, since you do not set right <link rel="icon" tag. There is no favicon there, so 404 Not Found occurs (anyway Express do not serve root folder by default).
Your CSP is published on "200 OK pages" only, so Express by default uses its own default-src 'none' for nonexistent pages (with status codes 404/403/500/etc).

This can really be confusing to anyone.

PS: Quite possible that the presence of %PUBLIC_URL% means you do not set PUBLIC_URL / homepage properly, because it should be substituted by a real folder/path. I just use your notation in the <link rel="icon" tag above.

PPS: I think if you add a custom error pages handler, it help to avoid similar misleading diag (code example you can take here).

UPDATE:

Cannot GET /

means webpack dos not know what page to show - defServer{...} output{...} sections misconfigured or wrong router(). Therefore you get 404 Not Found page. You could to look in the Developer tools is the Status Code 404/200 and which Content-Security-Policy HTTP header you have really got (here is a tutorial).

In case of 404 Not Found, webpack shows built-in default error page (since you do not created your own). This error page is served with default webpack's CSP, not yours (your CSP will be published on pages with 200 OK status code only).

I just searched all of the files in react-script, which is where webpack config files live, and don't find any occurance of "default-scr: NONE"

AFAIK, webpack-dev-server uses a finalhandler which rejects /favicons on 404 pages exactly with the same issue you have. In this way default-src: 'none' should be in node_modules/finalhandler/index.js.

Why am I dealing with CSP with this CRA app and not the other dozen I created the same way?

Previously finalhandler has default-src 'self' so /faficons was not blocks by CSP. But after this thread: default-src should be 'none' in finalhandler at May 2019 - things changed.

I guess you issue is not CSP related, it's just have misconfigured defServer{...} or output{...} (some path: __dirname + 'public/' or publicPath: points to a wrong dir).
CSP error is only a symptom (bad thing it's a false symptom) of the disease, but we need to treat a cause but not symptoms.

PS: I think instead of %PUBLIC_URL%/favicon.ico it should be http://localhost/favicon.ico in HTML, it's something misconfigured here too.

granty
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  • Hello granty, thanks for the response. I have done as you suggested & still getting the same error. I neglected to mention I am working in dev. I used CRA to start. I wonder if I need to define the path for my public folder somewhere? My html contains in the head and my file structure is thus: Project->client->public->favicon.ico. In manifest: "icons": [ { "src": "favicon.ico", "sizes": "64x64 32x32 24x24 16x16", "type": "image/x-icon" } ], Chrome Dev does not see the manifest.json, show stopper? Thnx – Bruggineer Nov 05 '20 at 23:03
  • Hi Bruggineer. I updated the answer, hope it helps you to find the real cause of the issue. – granty Nov 06 '20 at 11:11
  • granty- it was the fact that Express does not serve the root folder by default. Once I corrected index.html to and added app.use(express.static('client/public')); and app.get("/favicon.ico", (req, res) => { res.sendFile(path.resolve(__dirname, "/favicon.ico")); }); to my server.js. THANK YOU! – Bruggineer Nov 07 '20 at 01:45