When a new version of a debug adapter firmware (fw) is available, Simplicity Studio (SSv5) will show a message asking if the user wants to update to the latest firmware version.  When the update is selected it will sometimes fail, especially on Windows, usually with a timeout message.  Silicon Labs is working on providing a fix to the issue through a combination of Simplicity Studio and Simplicity Commander updates (Simplicity Commander is used for all adapter fw updates, even through SSv5).  Until a fix is available, the following procedure can be used to update the adapter firmware.
1. From the [Tools] menu, open Simplicity Commander.

2. Exit Simplicity Studio, but keep Simplicity Commander open.  Simplicity Studio inadvertently interferes with the update process when the debug adapter is reset in bootloader mode.

3. In Simplicity Commander, click the [Select Kit...] button and then select the debug adapter to update.  If an earlier adapter firmware update attempt failed, there may be a popup about the adapter being in 'bootloader mode', that is fine, just ignore the message and hit the [OK] button and proceed with the next step.



4. The [Kit] section of commander should be selected.  In the [Update Kit] section click the [Browse...] button to find the update image to use.  The various adapter firmware images for the debug adapter types that have been attached to the computer will have been automatically downloaded to the 'offline/hwtools/firmware' folder in the SSv5 installation folders (under Contents/Eclipse on MacOS).  If only one adapter type has been attached, then there will only be one folder and the latest file in the folder should be selected.  But there could be several adapter firmware folders from amongst this set:


Note: If the wrong adapter firmware image is selected it will not hurt anything as that will be detected and the update will be aborted. So, in the worst case a trial and error approach can be used.

The various adapter firmware images exist because there are different board controller processors on the various debug adapters.  The following is a guide for which adapter firmware group (examples S1015B, S1015D, S1015E, S1015F) should be used for the various Silicon Labs debug adapters.
S1007 - Older EFM32 development kits with 'DK' in part number
S1010 - EFM32 based starter kits, BRD2001A, BRD2100A
S1012 - BRD3201A, BRD3201B
S1014 - EFM32 based starter kits, BRD2010A, BRD2200A, BRD2201A, BRD2400A
S1015A_mcu_stk - EFM8 and EFM23 based starter kits, BRD5000A, BRD5001A, BRD5100A,
              BRD5101A, BRD5200A, BRD5201A, BRD5202A, BRD5300A, BRD2012A, BRD2102A, 
              BRD2204A, BRD2204B, BRD2500A, BRD2501A 
S1015B - Wireless mainboard BRD4001A and BRD4001B, also known as 'WSTK'.
S1015C - Thunderboards, BRD4160A, BRD4166A, BRD4166C, BRD5002A
S1015D - For the various small 'devkits' such as Thunderboards and the 26xx boards.
                BRD1015A, BRD2503A, BRD2503B, BRD2600A, BRD2601B, BRD2602A,
                BRD2603B, BRD2605A, BRD2608A, BRD2700A, BRD2701A, BRD2702A,
                BRD2703A, BRD2704A, BRD2705A, BRD2710A, BRD2900A, BRD2901A, 
                BRD2902A, BRD2903A, BRD2904A, BRD2905A, BRD4108A, BRD4184A, 
                BRD4184B, BRD4314A, BRD4330A, BRD4331A
S1015E - Wireless pro kit - BRD4002A, also known as 'WPK'.
S1015F - Pro kit, EFM8 and EFM32 based 'B' and 'C' variant boards, 
                BRD2001B, BRD2010B, BRD2012B,
                BRD2100B,  BRD2102B, BRD2200C, BRD2201B, BRD2204C, BRD2400B,
                BRD2500B, BRD2501B, BRD2504A, BRD5000B, BRD5001B, BRD5100B, 
                BRD5101B, BRD5200B, BRD5201B, BRD5202B, BRD5206B, BRD5207B,
                BRD5208A, BRD5300B,
After opening the latest file in the appropriate folder, click the [Install Package] button.  The progress of the update can be tracked in the Log Window.  If the update fails, then close any dialog boxes and try again with the following two notes:
1. If an EMLINK failed message is received, then disconnect and reconnect the debug adapter before trying again.
2. If the blue LED near the USB connector is flashing fast (this has only been observed sometimes on Windows), then wait for the flashing to stop before trying again.  My observation is that if the blue LED starts flashing for a long time when a debug adapter is connected, then rebooting the PC will resolve that issue.

The above procedure has worked every time it has been tried, sometimes it might take up to 4 or 5 attempts to update the firmware.

This issue will be fixed with the Simplicity Studio SV5.10.0 and Simplicity Commander 1v17p0 release.