You did use the proper USB port on the -050 board? On my board its labeled J1. Also, try to change the USB cable, sometimes they are bad.
You may try the following:
1. Check that you have selected correct Device. First Open your Project. Then from the top menu bar, select:
Project -> Device Selector...
and then select the device id that you are using from the list.
To know your device id, you may either see the cypress PSoC chip on your board -- it is usually printed on it (for example: CY865868AXI-LP035). Otherwise, open an example project (File -> Example Project..) and check the device id it has used (by checking 'Project -> Device Selector...' list). Yoy may try to compile and program the example project to check whether the error is due to USB cable or improper configuration setting.
2. More often than not, the problem is due to USB cable or your PC USB port. Try to use other cable/PS USB port. Also make sure to use right USB port on PSoC board for programming (the one which is near to the edge).