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How to apply the license key?

Scheduler .NET is distributed under Commercial and Enterprise Licenses. Once you buy a license, you get the license key (over email) that you need to use to activate the library.

Please, don't mix up the license key with the license number. These are different things.

To activate the scheduler you need the license key. In the confirmation letter the key looks like this:

The key is applied in the app settings of the web.config file as shown below:

        <add key="dhx_license" value="putYourLicenseKeyHere"/>

As the value of the dhx_license key you should specify your license key.


  • If the dhx_license key has the empty value or isn't added to the web.config, Scheduler .NET will work in the trial mode (fully functional within 30 days of the build date).

  • If you specify an invalid key or the trial period has passed, Scheduler .NET will throw an exception, once an instance of DHXScheduler is created.


If the license key does not pass the validation, the component throws an exception. The exception message usually contains the error description:

  • Evaluation period has expired. Please contact us here or send us an email - is thrown after your evaluation period expires - by default it's 30 days from the first use of the component, or the expiration date of evaluation license key.
  • Couldn't verify evaluation period. Please contact us here or send us an email - fires when the online trial period check fails. Can be solved obtaining an offline license key here.
  • Invalid license string - the value of 'dhx_license' was not recognized as a license string of dhtmlxScheduler. It may mean that you've mixed it up with some other value, like the customer key for support system.
  • Failed to check credentials - the component was not able to verify the license key. It can happen if you didn't copy all characters of the license key, or added an extra character, or modified the key in some other way.
  • Invalid credentials - it usually happens if the key has been modified or it's not genuine.

If the problem can't be solved, feel free to contact DHTMLX support team at or notify us via email.

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