Loading large JSON data files into Powershell

json.ps1

# Work around on
# ConvertFrom-Json : Error during serialization or deserialization using the JSON JavaScriptSerializer. The length of the string exceeds the value set on the maxJsonLength property.

$json = New-Object -TypeName System.Web.Script.Serialization.JavaScriptSerializer
$json.MaxJsonLength = 104857600 #100mb as bytes, default is 2mb

$filedata = [System.IO.File]::ReadAllText($JSONDataFile) #Using default encoding
$data = $json.DeserializeObject($filedata, [System.Object])
$filedata = $null
$json = $null

works like a charm when usint $json.DeserializeObject($string) (see also https://docs.microsoft.com/de-de/dotnet/api/system.web.script.serialization.javascriptserializer.deserializeobject?view=netframework-4.8)

Updated the Gist based on this. I haven't tested this. I assume this comes back to Powershell/.NET version at the time I originally wrote the script.

May be it is too late here as i have come across searching for similar references... The solution provided works very well. But we need to make sure that the content is saved without conversion by Invoke-RestMethod which will automatically does the conversion if the stream size is less than default max Json length otherwise the content is written to the file as is. The problems mentioned by kbbgl and ntarakaram1980 are observed in case where the payload size is less. So it is always better to save the content with (Invoke-WebRequest -Uri 'Uri').Content instead of Invoke-RestMethod to ensure that it doesn't convert the payload automatically based on the size.

Not sure if my original issues was loading data out of a file or off a web request, thanks for the additional note.