Keil Logo

LICENSE: Troubleshooting: Argument '*' not permitted for option 'cpu'

Information in this knowledgebase article applies to:

  • MDK-ARM from v4.60 to v5.11
  • ARM compiler


My MDK-ARM product is using a FlexLM license. After a Windows system crash, I cannot compile and build my existing projects anymore. When I build my project, I always get the following error:

error: A3903U: Argument 'Cortex-M3' not permitted for option 'cpu'.

I tried uninstalling and reinstalling the MDK-ARM, but still no success. How can I solve this issue?


This issue caused by system crash or power outage usually happens for FlexLM license users.

In order to solve this issue, please check if there is a file named *mdk_* somewhere in the User or System temp directories. It is named slightly different depending on the license type you are using.

If you find something like LLF5.0201305mdk_std37xxx7302xxxx919xxx or similar (mdk_std depend on your license), please delete this file. But make sure to create a backup before deleting it.

Please NOTE that this issue has been resolved in MDK v5.12 or higher.


The following Discussion Forum threads may provide information related to this topic.

Last Reviewed: Thursday, October 17, 2019

Did this article provide the answer you needed?
Not Sure
  Arm logo
Important information

This site uses cookies to store information on your computer. By continuing to use our site, you consent to our cookies.

Change Settings

Privacy Policy Update

Arm’s Privacy Policy has been updated. By continuing to use our site, you consent to Arm’s Privacy Policy. Please review our Privacy Policy to learn more about our collection, use and transfers
of your data.