Thumbnail Previews not showing in Windows 10 File Explorer

Use Disk Cleanup to remove your thumbnails

Your thumbnails use thumbnail cache, but if the thumbnail cache is corrupted you might experience this problem. To fix the issue, you need to remove the thumbnail cache and Windows will recreate it. This is a simple process and you can do it by following these steps:

  1. Press Windows Key + S and enter disk cleanup. Select Disk Cleanup from the menu. Alternatively, you can just open the Start Menu and type disk cleanup to search for it.
  2. Once Disk Cleanup starts you’ll be asked to select the drive you wish to scan. Select your System drive, by default it should be C, and click on OK.
  3. Wait while Disk Cleanup scans your drive.
  4. When Disk Cleanup window appears, check Thumbnails from the list and click on OK. Few users are suggesting to select Temporary files as well, so you might want to do that.

Windows will now remove the thumbnail cache from your PC. Once the thumbnail cache is removed, Windows will generate it again and your problem should be resolved completely.

There are 21 different ways to fix this, No. 7 is working for me, so I copied it here. This is the source URL:

Also other reference:


Windows Server 2012 R2: How to add the DHCP role using PowerShell?

Found this blog quite helpful in the middle of a deployment, when getting “Failed to open the runspace pool. The Server Manager WinRM plug-in might be corrupted or missing” in GUI. So PowerShell is more capable if you are confident what you are doing. Here is what I put in the ISE to execute one by one.
Install-WindowsFeature DHCP -IncludeManagementTools
Install-WindowsFeature WINS -IncludeManagementTools


The following is a sample chapter from the e-Book Windows Server 2012 R2: How to install and add roles? (Server Core). Enjoy reading!

This is what people need: an easy-to-deploy, easy-to-use tool.” Nat Friedman

What is Dynamic Host Configuration Protocol (DHCP)?

Basically, Dynamic Host Configuration Protocol (DHCP) is a computer network protocol that assigns IP addresses to computers on a network. The working principle of DHCP briefly is described through the acronym DORA which means Discovery, Offer, Request, and Acknowledgement. In a computer network, when you turn on your computer and the operating system boots up the DHCP Client service transmits the request for an IP address. In fact, this request is an attempt to identify whether or not a DHCP server is available on a LAN. If it is, the DHCP server accepts the DHCPDISCOVER message from the client, reserves an IP address for the client, and…

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“The RPC server is unavailable”

In the scenario of getting event logs remotely, using Event Viewer or PowerShell, some time in an unfamiliar environment, the system admin may get this error “The RPC server is unavailable” even the correct credential is supplied.

Why? The service is running on the remote host – most of the time it’s a Windows Server. There must be something block the traffic – Windows Server itself or the network.

Look into the Windows server – the target host, there are several places to check – The Windows Firewall, the Group Policy. Many online resources focused on WMI Group rules, such as running the following command to enable this group of firewall rules – 3 Inbound and 1 Outbound.

> netsh advfirewall firewall set rule group=”Windows Management Instrumentation (WMI)” new enable=yes

The same approach is to open 3 Inbound rules using Windows Firewall with Advanced Security or GP Editor:

Computer Configuration
– Windows Settings
— Security Settings
— Windows Firewall Advanced Security
—- Inbound Rules
—- Right-click and select ‘New Rule’ (Key point)
—- Predefined radio button
—- Choose Remote Event Log Management (Drop down list)
—- Click Next
—- Accept the defaults and click ‘Next’
—- Choose Allow the connection and click ‘Finish’

But, sometimes these local firewall rules are already enabled, by default, unless they are disabled on purpose. Then what?  There is another place to look at, despite the message “The RPC server is unavailable”, some newer operation systems give more information in a pop-up.


Now look at these two rules, they could be disabled, just enable them you will be able to access Event Logs remotely.

This is tested in both Event Viewer and PowerShell, on Windows Server 2012 R2.

p.s. I don’t think .Net Framework 3.5 is necessary in this case, some online article mentioned that though. But still worth to check if the following services are running on the target host:

  • Windows Management Instrumentation service
  • TCP/IP NetBIOS Helper service
  • Remote Procedure Call (RPC) service

Remote Desktop Services (RDS) in Azure

It is a Dev/Test environtment available to all Azure subscribers. I tried this out and it is not too bad. In my opinion, this is the way to go for Microsoft, because it provides a package to potential customers that are not quite familiar with how Azure environment is to be built, either for the PoC purpose or next, in production. Once people get more idea on how it works, there will be less barrier to adopt more in the cloud.

Traditionally, when we start build an infrastructure and services in data center, we started with IP allocation, physical location/rack/power supply, network patching, switches/load balancers, servers, storage, then firewall, iLO/DRAC, O/S build, license, etc.  But when we start in Azure, where I should start is a big question to many of us.  If one just wants to do some testing but need more than a couple of servers and in a small to medium scale, there is no sense to go through all the hassles.

This RDS testing package I set up over the long weekend is pretty simple to start with. Under the basic concept of MS Remote Desktop Services, you can go through the documentation and team blog first, then start picking the size and scale of the environment – redundency, vm size, etc.  At least you will need one DC on Windows Server 2012 R2, and three servers on Windows Server 2016 – RDSH, RD Broker, RD Gateway (including RD Web Access) – other service can be combined such as RD license server and file storage. So far I don’t see there is firewall between them like the diagram showed, all testing servers are in the same subnet (10.0.0.x), of course Azure would guard everything that are accessible from the Internet.

Most steps are straight forward as I did before for  the similar services. Only a few places in the document maybe still referring to a different version of Windows Server (2012 R2 vs 2016 or vice versa).

Remote Desktop Services @ MS Docs

Windows Server RDS team blog site

First look at updates coming to RDS (Sept 2017)

Here are links to Windows Server 2012 based RDS:

Other team blogs, some are not current but future ideas:

Unrelated links:

STOP: 0x000000C4 after installing KB4056894 – I guess M$ has used too many ¢heap resources recently…

My old Dell desktop (Dimension C521, AMD Athlon 64 X2 Dual Core 3600+) got hit twice since Saturday and did not recover from the blue screen yet (it was finally fixed 30min ago). It runs Windows 7 and of course, it is “AMD inside”. Some online forum said this is caused by the friendly fire from Microsoft who tried to fix the Spectre and Meltdown which affect Intel chips.

I have left my desktop on automatic-update since its upgrade to Windows 7 and I left it in sleep mode or running state most of the time. Last Saturday morning, I found it stuck at a blue screen, which seemed new to me, because it didn’t show a lot of information like a normal blue screen does.


I was lucky on Saturday. After cycled the power, the try-normal boot didn’t work, so I tried to let it fix by itself and it works. It looked like nothing happened after that and ran without a problem for 3 days.

Last night, I left it run overnight, then in the morning, I saw the blue screen again. I tried to fix it used the same option as last time, several times. It didn’t work. So I did some research and found the following, I may try them after work today.

BTW, I don’t have third-party anti-virus installed on my PC, only have MS Security Essentials and that is up-to-date.

After 3 days, MS gave sort of acknowledgement, but no fix yet.

Okay, after some research and thoughts, I started to recover my PC when I got home.

First thing I tried is to let it boot and recover by itself, as expected it failed, the same as this morning. Then, I choose an advanced mode in the same session, and managed to get to a DOS prompt, but when I use the DISM command to remove the package, it gave me error said something about running mode. So I stopped there, went to the basement to find the Windows 7 installation disk.

Next, I use the Windows 7 installation DVD to boot the PC, went into recovery mode, similar interface as last try, I got the DOS prompt, and I ran the same DISM command, this time it had some progress as showing here:


It took a while and at the end, it’s a success.


After reboot, it still tried to finish the last “failed” update and stuck in this screen for quite some time.


Then it let me login, everything seems back to normal, except in the update history I saw this.


The latest pending update was the culprit, it still showed Pending state, but after a few minutes and a pop-up message, the status changed to Failed.

So that’s the adventure lately, and here is the command I ran, copied from one of those online communities.

dism /image:d:\ /remove-package /packagename:Package_for_RollupFix~31bf3856ad364e35~amd64~~7601.24002.1.4 /norestart /scratchdir:d:\temp

Some thoughts though, after this. What about many other normal users, homeusers, system admins?  Let’s wait and see how Microsoft can fix this for thousands if not millions of AMD-based PCs/servers when they are in bricked mode.




Web + Mobile



Data + Analytics

AI + Cognitive Services

Internet of Things

Enterprise Integration

Security + Identity

Developer Tools

Monitoring + Management

Azure Stack

Sovereign Clouds







What are these Office 365 URLs about?

Admin Portal Home:

Under that, the different Admin Centers’ URL naming convention is in a quite mess.

Exchange is

Skype for Business is

SharePoint is

Under SharePoint, there is an OneDrive document repository for every user:, it actually resolves to Other than that, there are sites and teams, and the new stuff – groups.

Default site collection:

Video Portal:



Compliance Policy Center:

OneDrive is

PowerApps is

Flow is

Security & Compliance is

Azure AD is