After linking two local Excel files by a simple reference to a cell in another workbook, I began seeing an ominous error:
SECURITY WARNING Links to external sources could be unsafe. If you trust the links, click Update. Click for more details.
This behavior was observed in version 1907 of Excel from the Office 365 software package.
Warnings of this nature should be taken seriously. In this case, however, the message has been seriously mislabeled. Clicking into the details brings up an ancient Help page for Excel 2007. Searching for similar situations online brings up some misleading instructions.
If you are experiencing the situation described above, continue reading below for a simple workaround and more background information.
Someone attempted a very noisy attack against my router’s built-in OpenVPN server today. While there was no chance this person could guess my encryption parameters to gain access, he or she did manage to cause a denial of service.
But that doesn’t solve the problem. Fine-tuning or even disabling the slow-link mode forces the Client Side Cache (CSC) to use its “Action on server disconnect” configuration any time the network isn’t performing perfectly. The default behavior, “Work offline”, treats each affected (meaning cache-enabled) share as being totally unavailable and then the CSC attempts to retrieve cached copies. This happens even if the server is still available but failed a single ping check.
Why is this still a problem? Well, in practice, most files don’t need to be available offline. By default, the Windows file server is configured, and the Windows client is designed to allow each user to select individual files as “Always available offline” from the file context menu. When a user selects this option, that one file is copied to the CSC, and in theory that one file is always available. This allows for targeted use and minimal sync time. The problem arises with all the other files. When the CSC goes offline and marks the shared folder as disconnected, it effectively blocks access to all the files that were never cached, even if the server and its files are still available.
At this point, you and I now understand the situation that needs to be avoided. We don’t want to have a large number of files under the unnecessary clutches of the CSC, regardless of network quality.
At first, I thought the solution was to change the file server’s default configuration of allowing users to decide which files are cached. I changed folders that needed maximum online availability to be set to “No files or programs from the shared folder are available offline.” This server setting automatically disables the CSC.
Unfortunately, the result was that the folders configured for offline caching worked great, but the folders configured for no offline caching only worked until some network error or server reboot. In this configuration, once a path became disconnected, an Offline Files message is logged in the Event Viewer, and even though no files are being cached the entire path becomes unavailable. At that point, the workstation persistently throws Error 0x80070035 any time that particular path is accessed, until the workstation is rebooted.
The only solution I’ve found that works now is to completely disable the Offline Files feature on the workstation. With Offline Files disabled from the Control Panel, the network and server errors are now transient and I am not having any problems with disconnected paths or persistent errors.
Offline Files is ultimately broken and does not improve the Windows experience.
I just resolved a long-term problem where one specific Windows 2012 server was unable to ping one specific device on the same LAN.
There were no relevant resources or similar-looking cases on the web. Everything else on this LAN worked normally. The server could ping all other clients, and the clients could ping the server and the NVR. I just could not get the server to ping the NVR for the life of me.
I suspected at one point that this was a routing issue due to my desire for strong security policies around IOT devices. This turned out not to be the case as I could find nothing wrong with the router or any routing tables.
At last, I decided this problem was so specific that it could be a bug in the NVR itself. In this case, the only thing special about the Windows server from the NVR’s perspective was that the server was providing both DHCP and DNS to the NVR. I tried disabling each service, and found exactly what I was looking for.
The NVR will not respond to pings from its DNS server.
I don’t know why this is broken and don’t really care to investigate any further. The workarounds are either:
Create a DHCP reservation with its own option to specify a 3rd-party DNS server, OR
Disable the NVR’s DHCP client and set a static address with an alternative DNS server address value.
In my case, the NVR does not need to use the local DNS server, so this is an easy fix. So long as my server’s IP address is not used in the NVR DNS configuration, everything works normally and the server can ping the NVR.
The ownCloud community dropped support for Windows Server, so I must resort to documenting such problems here instead of contributing open source.
One major symptom that confirmed ownCloud was using more than one PHP environment on my server was the presence of session handler files in more than one directory. Specifically, I was finding orphaned files in C:\WINDOWS\Temp even though my one and only php.ini production file specified a different path as well as garbage collection.
I traced the session file generation as far as the ownCloud calendar “app”, which lives in owncloud\apps\calendar\appinfo\remote.php and related places.
Debugging results were fascinating in that not only was the wrong configuration file loaded, after dumping all phpinfo() to disk I also found that the calendar app was running under an entirely different version of PHP.
The culprit: After the most recent PHP upgrade, my site-specific Handler Mappings ended up with mismatched verb restrictions. Somehow the new version ended up restricted to GET,HEAD,POST by default, while the old version remained unrestricted. Although my handlers were in the correct order to give all *.php files to the correct module, any time a CalDAV client sent a PROPFIND or similar request, IIS essentially downgraded to the unrestricted version of PHP.
The solution: Remove verb restrictions for the ownCloud site’s Handler Mappings, and then remove all but one of the PHP Handler Mappings to prevent any other versions from running without throwing errors.
If you get a bogus error about spaces in “the path to the script processor” when updating verb restrictions, just add double quotes around the path, and then click “No” on the ensuing bogus error about needing to create a new FastCGI application. (facepalm)
I just tried taking a Windows 10 laptop on the road for the first time. Everything was great until I tried the VPN for the first time. Suddenly, I was getting Access Denied errors, and “You do not have permissions” errors for all files made available offline. I confirmed the VPN tunnel and even browsed to other shared folders on the same server. The offline files errors persisted after dropping the VPN.
When I returned to the domain Wi Fi, file synchronization completed normally and there were no errors at all.
Am I to believe that Windows 10 is completely incompatible with VPN synchronization? I never had a problem with this on Windows XP, and I am dreading the months of research and experimentation normally involved in fixing this kind of Microsoft failure.