Core issue
This error message is displayed in the show version output of your switch.
In some cases, the show test 1 command output possibly shows the NVRAM:F.
The global checksum error means that the next time the box is reloaded, the nvram most likely is lost due to a crc checksum that failed while it read the configuration. This is not usually a hardware error, but it corrects itself.
This does not have any impact to an operational switch unless configuration changes are made while the switch is in this condition. But most of the times, a reset resolves the checksum failure as it is re-calculated.
This problem is identified as per Cisco bug ID
Resolution
At this point, you need to back up the configuration and schedule a downtime in order to reboot the box and copy the configuration, if the configuration is erased.
If the switch is reset, it is possible that some configuration data is lost. Hence, before the switch is reset, make sure that you have a current copy of your configuration stored on another device. Issue the show config, then copy and paste it to a text file in order to accomplish this. After the reset, check the show version and the show test 1 output to ensure your switch is back to normal.
Refer to article How to upload the running configuration or a configuration file stored on the Flash device of a Catalyst switch to a TFTP server for more information on how to upload the running configuration to a TFTP server.
