Skip to main content

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…

Labels:

Popular posts from this blog

Podman– Command execution failed with exit code 125

After updating WSL on one of the developer machines, Podman failed to work. When we took a look through Podman Desktop, we noticed that Podman had stopped running and returned the following error message: Error: Command execution failed with exit code 125 Here are the steps we tried to fix the issue: We started by running podman info to get some extra details on what could be wrong: >podman info OS: windows/amd64 provider: wsl version: 5.3.1 Cannot connect to Podman. Please verify your connection to the Linux system using `podman system connection list`, or try `podman machine init` and `podman machine start` to manage a new Linux VM Error: unable to connect to Podman socket: failed to connect: dial tcp 127.0.0.1:2655: connectex: No connection could be made because the target machine actively refused it. That makes sense as the podman VM was not running. Let’s check the VM: >podman machine list NAME         ...
Read more

Cache stampede: when our cache turned against us

While investigating some performance issues, we ran into an ASP.NET Core API that cached a fairly expensive aggregation query for 60 seconds. Under normal load, that was fine: one request rebuilds the cache, everyone else reads from it. Under peak load, dozens of requests would arrive in that same expiry window, all see a cache miss, and all fire the same expensive query in parallel. The database didn't like that. That was the moment when our caching layer stopped helping and started hurting. A burst of requests comes in at the same time, all miss the cache, and all go hammer the database or the downstream API at once. That's a cache stampede . The cache was supposed to protect our backend, and for a few hundred milliseconds it did the opposite. Why this happens IMemoryCache.GetOrCreate (and its async sibling) looks like it protects you, but it doesn't add any locking on its own. Look at the naive version: public async Task<Report> GetReportAsync(string key) ...
Read more

Azure DevOps/ GitHub emoji

I’m really bad at remembering emoji’s. So here is cheat sheet with all emoji’s that can be used in tools that support the github emoji markdown markup: All credits go to rcaviers who created this list.
Read more