Symptom

 When attempting to reach BarTender Print Portal, you may receive the following error message:

Server Error in '/BarTender' Application.

Could not load file or assembly 'BtSystem.Client' or one of its dependencies. An attempt was made to load a program with an incorrect format.

Applicable to

BarTender 2019

BarTender Print Portal

Solution

The application pool running BarTender Print Portal is running in 32-bit compatibility mode. It will need to be turned off for BarTender Print Portal to properly load.

1. Open the IIS Manager (which is accessible within Windows Control Panel > System and Security > Administrative Tools > Internet Information Services (IIS) Manager)
2. Click on Application Pools
3. Right click on the pool running BarTender Print Portal (by default, this is BPP_AppPool)
4. Go to Advanced settings
5. Change the value next to "Enable 32-bit applications" to false

6. You may need to restart all the BarTender services (excluding BarTender Licensing Service and Printer Maestro) before this setting is applied. To restart BarTender services, open BarTender Administration Console and go to the Windows Services tab. 

7. Once BarTender services have been restarted, restart the site by restarting the World Wide Web Publishing Service within Windows Services then try to access Print Portal again.