On 64-bit Windows 7 or Windows 8.1, the 64-bit version of SyncBackPro or SyncBackSE fails to start and Windows shows this error:
The program can't start because api-ms-win-crt-string-l1-1-0.dll is missing from your computer.
Reinstalling SyncBack will not fix it.
Cause
The 64-bit SyncBack executable needs the Microsoft Universal C Runtime (UCRT), and api-ms-win-crt-string-l1-1-0.dll is part of it. Windows 10 and 11 include the UCRT. Windows 7 and 8.1 only have it if the Microsoft update KB2999226 (Update for Universal C Runtime in Windows) is installed, or a later update that replaces it. PCs that have not run Windows Update for a long time, or that skip Recommended updates, often don't have it. The same applies to Windows Server 2008 R2 and 2012/2012 R2.
Solution
Install the Universal C Runtime using one of these methods, then start SyncBack again:
1. Windows Update (recommended). Run Windows Update and install all available Recommended updates. The UCRT is offered as a Recommended update.
2. Install the update manually. Search the Microsoft Update Catalog for KB2999226 and install the x64 package for your version of Windows.
3. Install the Microsoft Visual C++ Redistributable (x64). If the UCRT is missing, the redistributable installs it.
Prerequisites: Windows 7 needs Service Pack 1, and Windows 8.1 needs update KB2919355 (April 2014). On Windows 7, if the update fails with error 0x800b0001, first install the SHA-2 updates KB4474419 and KB4490628, restart, and try again.
A restart may be needed after installing the update.