Windows 10 Server Service Bug Documentation January 10, 2020
A serious flaw that is observed in the Windows 10 system versions 1903 (19H1 build 18362) and 1909 (19H2 build 18363) can cause serious performance degradation for the average user following a Windows operating system upgrade.
Symptoms: Following a Windows 10 operating system upgrade to version 1903 PC performance slows to a crawl. Some access to the file system results in a delay waiting for a response.
Simple Explanation:
The problem is caused (and you can induce the problem) by having a computer description name that is longer than 127 characters. This data is typically viewed or changed by the System screen found at Control Panel\All Control Panel Items\System. When this computer description name is longer than 127 characters while running a prior version of Windows 10 version (for example version 1803 Redstone 4 or 1809 Redstone 5), the Windows automated update to these versions can cause the problem to appear. This is a serious problem for the average user since he will not know what is causing the problem and there is no automated way to fix.
What complicates this bug is that once the computer is rebooted the problem persists and the change to the computer description name in Control Panel\All Control Panel Items\System no longer functions so the average user does not have a simple way to correct the problem. The only solution is manually edit the Registry, which is not something a typical user is accustomed to doing.
Affected Windows 10 versions: 1903, 1909
To display your current version of Windows run winver from the Windows search box or C:\Windows\System32\winver.exe.
Other Symptoms:
* starting File Explorer is delayed
* creating a directory is slow
* deleting a directory is slow
* accessing a directory is slow
* closing File Explorer takes long
* switching user is slow
* File Explorer showing drives is delayed
* Notepad open dialog box, initially slow, second try is fast, consistently doing this
You can see if your computer has this problem by launching Windows File Explorer (keyboard shortcut, Windows key + E), right click on ‘This PC’ and select Properties. If your system is having this problem, what will be displayed is “Computer Description: Not Available” and “Workgroup: Not Available”. Another path to this screen is Control Panel\All Control Panel Items\System. If your computer displays something other than “Not Available” then your computer is NOT affected by this bug. Here is a picture from an affected system:
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Simple Solution to problem when the computer is running slowly:
1) From the Windows start box type in the box Regedit. You may need to have administrator privileges to run this program. Launch Regedit.exe, and traverse the directory tree until you get to Computer\HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\LanmanServer\Parameters double click to edit the registry entry for “srvcomment”. A pop up box that says “Edit String” will appear. Edit the entry and make the entry shorter, 127 characters or less and click on OK. This allows you to change the System ‘computer description’ even when that ability is disabled in the System control panel box.
2) Next, exit Regedit and reboot the system, the problem should be corrected
Complex Detailed Explanation and Solution:
Service name: LanmanServer Service display name: Server
To view how the problem is rendered, run the Services application found at (C:\Windows\System32\services.msc) and locate the Server service. Stop then start the Server service.
You will see a pop up box that will display the message “Windows could not start the Server service on Local Computer.” “Error 13: The data is invalid.” error to appear in a dialog box (message window).
You can correct the problem on a running system without the need for a reboot. Run Regedit.exe and follow the instructions in step 1 above to edit “srvcomment” found at Computer\HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\LanmanServer\Parameters and make the entry 127 characters or less. Now run the Services application found at (C:\Windows\System32\services.msc) and locate the Server service. Stop then start the Server service. You may see warnings regarding the Computer Browser service dependency on the Server service, this is normal. in Computer Browser depends on Server and does not affect the performance problem. This service should not start without an error. Below are pictures of the services error dialog box and a picture of the regedit screen.
Submitted by Guy Simonian and Christopher Paulin of Check Fund Manager.
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