Arm Mbed OS support forum

Mbed Studio 1.0 License error on Mac 10.14.6

[ERROR] armclang: error: System clock tampering detected. License checkout will fail.

I installed the new Studio on my Mac, I still get the licensing error like I had in the previous version. I am waiting for a solution now for more than 7 month?

Please drop me a e-mail to to get this resolved.
PS: I even own a Keil MDK license which I use on Windows.

Regards Helmut

PS2: I even created a second user account on my Mac, the problem continues.

Hi Helmut,

Apologies that this issue is still present in Mbed Studio for you. We have added it recently to known issues as we have few users experiencing it: We have recently found a false positive case when this issue can happen. It seems to be related to change of region on your system. We are working with Compiler team on fixing it.

Arek - Mbed Studio team

Good morning Arek, we created a new Mbed based IOT LoRa solution ( and are selling this product now with full compatibility for Mbed-OS 5.

I love to use my own Mac for running the Mbed Studio (instead of using it in a Windows VM or on another Mac).

It would be great if you can make a contact to the responsible team to help to get this fixed, I don’t like to re-install my Mac from scratch because it takes me 2 days or so.

Thank you for organizing help for my installation.