1. Error while preparing Storage Group [First Storage Group] for backup: "An Incremental/Differential log backup cannot be performed when circular logging is enabled.”
2. This error typically occurs when the circular logging option is enabled or when the circular logging option has been changed without restarting the information store or running a full backup after the change.

To resolve this issue, follow the steps below:

Step 1: Disable Circular Logging

1. Open Exchange System Manager.

2. Navigate to Administrative Groups -> Your Administrative Group -> Servers -> Your Server -> The Storage Group you want to check.

3. Right-click on the storage group, select Properties, and uncheck the “Enable Circular Logging” option.

Step 2: Restart Information Store Service

1. Restart the “Microsoft Exchange Information Store” service.

Note: After disabling circular logging, it's essential to run an additional full backup. Follow these steps:

1. Go to the menu “List Backup Schedules -> Edit (Action Icon for the particular backup job).”

2. Below the title ‘Advanced Settings,’ check the option ‘Run additional full backup after saving this configuration.’