[German]Microsoft released a cumulative update KB4512941 and a Servicing Stack Update (SSU) KB4515530 for Windows 10 Version 1903 on August 21, 2019. This should finally fix the sandbox problem. However, the updates don't seem to be distributed 'officially' yet. It's tested in Release Preview ring.
A list of the updates can be found on this Microsoft website (currently not documented). The update installation requires an existing current Servicing Stack Updates (SSUs). Microsoft now publishes an overview of current Servicing Stack Updates (SSUs) under ADV990001. The Windows 10 versions up to version 1709 are no longer supported in Home and Pro – only the Enterprise versions receive the updates there.
Update KB4512941 for Windows 10 Version 1903
Cumulative Update KB4512941 (dated August 21, 2019) raises the OS build to 18362.325 and includes quality improvements but no new operating system features.
Currently, Microsoft has not yet updated its documentation and does not provide it in the Microsoft Update Catalog. The update is mentioned here. And the colleagues from German site deskmodder.de writes here that the sandbox finally works (in Windows 10 systems with language settings other than English, see Windows 10 V1903: Update KB4497936 breaks Sandbox) after the update installation.
Currently still quite buggy
Due to the lack of documentation from Microsoft, not much can be said yet about the fixes of this update. According to this comment the sandbox bug has been fixed only partially (some programs developed won't run within the sandbox environment). In the comments of deskmodder.de it is also criticized that the search does not work and Cortana runs with 44 % CPU load.
User Ben writes here that a registry entry is the cause. He suggests the following reg file for import.
The entry forces the Bing search, whereupon the CPU load for Cortana decreases and the search also works. However, another user cannot confirm this, Cortana continues to run at high load. By the way, the problem has been there for 2 weeks at Windows 10 19H2 Insider Preview and nothing is happening at Microsoft. Deskmodder has added the information that the problem only occurs if users have changed the search settings. As soon as the search index is rebuilt, the load should go back. The region setting German/Austria should also help with the Cortana load (well, since Strache is gone, you don't have to search in Austria anymore). In the comments here some users mention that Windows wants to 'synchronize' itself when restarting. At the moment this update is more of a toilet exercise – maybe Microsoft is still testing and will release it on August 22, 2019.
Addendum: I've written a brush up with findings reported from my blog readers at Windows 10 V1903: MS investigating the Search/Cortana issue (09/03/2019). There you will find also a confirmation, that Microsoft is investigating the issue and plan a fix in upcoming releases.
Update KB4515530 for Windows 10 Version 1903
It is a Servicing Stack Update (SSU), which is mentioned here (unavailable). Also here there is no information from Microsoft available yet.
Microsoft Office Patchday (August 6, 2019)
Microsoft Security Update Summary (August 13, 2019)
Patchday: Updates für Windows 7/8.1/Server (August 13, 2019)
Patchday Windows 10-Updates (August 13, 2019)
Patchday Microsoft Office Updates (August 13, 2019)
Windows 10: Updates August 16/17, 2019
Windows 10 V1803: Update KB4512509 (08/19/2019)
Fix for VB6, VBA, VBScript bug?
Windows 10 V1903: Update KB4497936 breaks Sandbox
Windows 10 V1903: Sandbox fails with error 0xc0370106
Cookies helps to fund this blog: Cookie settings