Gateway Error .Net Framework 4.30319 yet 4.8 is installed

[DKHUghes55]

Hi Fabric Community

I'm seeing an error on our On-prem data gateway.  The error:

Application: Microsoft.Mashup.Container.NetFX45.exe
Framework Version: v4.0.30319
Description: The application requested process termination through System.Environment.FailFast(string message).
Message: Unexpected exception in background thread of Mashup container (error code -2146233088)

The gateway version is 3000.306.4 (Feb 2026)

.Net Framework 4.8.03761 is installed on the server.

Any one know why it appears it is using 4.0.30319 instead of the 4.8.03761 version?

Thanks,

DKHughes55

[MohdZaid_ · Accepted solution]

Hey @DKHUghes55 , 

This is one of those messages that looks scary but is actually a bit misleading at first glance so you’re not alone in questioning it.

The .NET version v4.0.30319 showing in the error does not mean your server is using .NET 4.0 instead of 4.8. In the world of .NET, versions from 4.5 all the way up to 4.8 are built as in-place upgrades on top of 4.0. Because of that, they all continue to report the same runtime version number (v4.0.30319). So even though your machine has .NET 4.8 installed, which is correct, the gateway process will still display that older-looking version string. That part is expected and not the problem.

The real issue is the Mashup container crash coming from the On-premises data gateway. The message about Microsoft.Mashup.Container.NetFX45.exe and the FailFast call usually means the Power Query engine (which runs inside the gateway) hit something it couldn’t recover from and terminated itself.

In practical terms, this tends to point to things like a heavy or problematic query, resource pressure on the server, or sometimes even a bug in the specific gateway version you’re running. It’s less about the framework and more about what the gateway was doing at the time.

A good next step is to look into the gateway logs and try to connect the error to a specific dataset or refresh. You’ll usually find the logs under the gateway installation folder, and searching for “Mashup” or that error code can help pinpoint which query triggered it. If you can reproduce the same query in Power BI Desktop, that’s even better it often surfaces the underlying issue more clearly.

It’s also worth checking the basics on the server itself. If memory or CPU is getting pushed hard during refresh, the mashup container can crash like this. A quick restart of the gateway service and clearing temporary files can sometimes stabilize things, especially if this just started happening recently.

So in simple terms: your .NET setup is fine, the version number you’re seeing is normal, and the focus should shift to the query, data source, or gateway behavior at the time of failure. If you can narrow it down to a specific dataset or connector, it becomes much easier to diagnose further.

If this explanation helped, please mark it as the solution so others can find it easily.

If it helped, a quick Kudos is always appreciated it highlights useful answers for the community.

Thanks for being part of the discussion!!!

[GilbertQ]

Hi @DKHUghes55 

I would also recommend that you make sure that you have got the recovery key for when you installed the Power RBI Gateway so that if you have to install this on another machine, you can then recover it to the other machine successfully with all your connections and source settings intact.

[Juan-Power-bi]

This is a common point of confusion — v4.0.30319 in the error doesn't mean .NET 4.0 is being used. That version string is actually the CLR (Common Language Runtime) version number, and it's been v4.0.30319 for all of .NET 4.x including 4.8. So 4.8 is almost certainly running correctly; the version string just looks outdated.
The real issue is the FailFast crash in the Mashup container with error code -2146233088 (which is 0x80131700 — a CLR initialization failure). That's what needs investigating.
A few things to check:
First, look at the gateway logs in %LOCALAPPDATA%\Microsoft\On-premises data gateway\GatewayLogs — the MashupContainer logs specifically will have more detail on what triggered the crash before the FailFast.
Second, check the Windows Event Viewer under Application logs around the time of the crash — there's often a more descriptive entry alongside the FailFast one.
Third, error code -2146233088 can sometimes be caused by a corrupted or missing .NET assembly, a TLS issue (the Mashup container making outbound calls that fail), or a memory/resource constraint on the server. If refreshes are happening in parallel, the container processes can starve resources.
Finally, since you're on the February gateway build, check if there's a March update available — there have been some Mashup container stability improvements recently. If the crashes are intermittent rather than consistent, it's likely a resource or timing issue rather than a configuration problem.