Blazor Wasm PWA IIS Deployment integrity error - iis

Question

I created a new Blazor PWA WebAssembly (last version default template) project and deployed it in a IIS in Windows Server to try PWA.
Installed the last .NET Core Hosting Bundle.
After publising it, I ran the script in the Microsoft Docs to rename dll files:
dir .\_framework\_bin | rename-item -NewName { $_.name -replace ".dll\b",".bin" } ((Get-Content .\_framework\blazor.boot.json -Raw) -replace '.dll"','.bin"') | Set-Content .\_framework\blazor.boot.json
And the serviceworker renaming code too:
((Get-Content .\service-worker-assets.js -Raw) -replace '.dll"','.bin"') | Set-Content .\service-worker-assets.js
Then I deleted the compressed files as the docs says:
wwwroot\service-worker-assets.js.br
wwwroot\service-worker-assets.js.gz
wwwroot\_framework\blazor.boot.json.br
wwwroot\_framework\blazor.boot.json.gz
But I am still getting an error when I load the app:
What Am I missing here?
I guess that it has to do with the hashes and the renaming thing but cant find any solution in the Blazor´s Github issues.

Answer 1

As a result of your modifications to the blazor.boot.json file, the integrity checks fails. service-worker-assets.js contains a list of files and their integrity hashes which are calculated at the time of publish.
You can manually recalculate the hashes using Bash/PowerShell, since you're using IIS, I'll provide the PowerShell script I used for a similar issue:
# make sure you're in the wwwroot folder of the published application
$JsFileContent = Get-Content -Path service-worker-assets.js -Raw
# remove JavaScript from contents so it can be interpreted as JSON
$Json = $JsFileContent.Replace("self.assetsManifest = ", "").Replace(";", "") | ConvertFrom-Json
# grab the assets JSON array
$Assets = $Json.assets
foreach ($Asset in $Assets) {
$OldHash = $Asset.hash
$Path = $Asset.url
$Signature = Get-FileHash -Path $Path -Algorithm SHA256
$SignatureBytes = [byte[]] -split ($Signature.Hash -replace '..', '0x$& ')
$SignatureBase64 = [System.Convert]::ToBase64String($SignatureBytes)
$NewHash = "sha256-$SignatureBase64"
If ($OldHash -ne $NewHash) {
Write-Host "Updating hash for $Path from $OldHash to $NewHash"
# slashes are escaped in the js-file, but PowerShell unescapes them automatically,
# we need to re-escape them
$OldHash = $OldHash.Replace("/", "\/")
$NewHash = $NewHash.Replace("/", "\/")
$JsFileContent = $JsFileContent.Replace("""$OldHash""", """$NewHash""")
}
}
Set-Content -Path service-worker-assets.js -Value $JsFileContent -NoNewline
This script iterates over all files listed inside of service-worker-assets.js, calculates the new hash for each file and updates the hash in the JavaScript file if it's different.
You have to execute the script with the published wwwroot folder as the current working directory.
I described this in more detail on my blog: Fix Blazor WebAssembly PWA integrity checks