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Blazor - Failed to find a valid digest in the 'integrity' attribute

After making a small change to a Blazor application, I redeployed it to an Azure App service. When I tried to open the updated Blazor application nothing happened.

When I opened up the browser console, I noticed a list of errors:

There are 2 errors important to explain what is going wrong:

Failed to find a valid digest in the 'integrity' attribute for resource 'https://cloudbreweshopweb.azurewebsites.net/_framework/dotnet.timezones.blat' with computed SHA-256 integrity '2NJf++ql6UnbRRdYWEir6MxH58bYGWDEqofII/z+Xmo='. The resource has been blocked.

Failed to find a valid digest in the 'integrity' attribute for resource 'https://cloudbreweshopweb.azurewebsites.net/_framework/dotnet.wasm' with computed SHA-256 integrity 'y0gwhQ7a6FTinj6R6HEA3SlRDb/iL70a56PEGpKbt/8='. The resource has been blocked.

This is related to the integrity checks executed by the browser.

Integrity checks

When Blazor WebAssembly downloads an app's startup files, it instructs the browser to perform integrity checks on the responses. Blazor sends SHA-256 hash values for DLL (.dll), WebAssembly (.wasm), and other files in the blazor.boot.json file, which isn't cached on clients. The file hashes of cached files are compared to the hashes in the blazor.boot.json file. For cached files with a matching hash, Blazor uses the cached files. Otherwise, files are requested from the server. After a file is downloaded, its hash is checked again for integrity validation. An error is generated by the browser if any downloaded file's integrity check fails.

There is a whole section in the Blazor documentation how you can troubleshoot this kind of error: https://learn.microsoft.com/en-us/aspnet/core/blazor/host-and-deploy/webassembly?view=aspnetcore-6.0#resolve-integrity-check-failures-1.

To get rid of this problem I did 2 things:

  1. I deleted the obj and bin folder for my Blazor app and recompiled the project afterwards.
  2. I reloaded the Blazor app using CTRL-F5 so that the browser cache is ignored.

That did the trick for me. Hope it helps…

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