You are facing an error “ Cannot start Microsoft Outlook.This may happen due to PST issues or malware attack. You are facing error “Operation failed” in Outlook when you are trying to reply.There are multiple signs for a corrupted profile or a damaged PST. Any type of hindrance or interruption during Outlook Data transfer.It is always advised to avoid such a situation. If you have a lot of folders or subfolders, then again you may face profile issues. Another reason is when the size of the PST file maxes out sometimes the size of a PST is limited, and when users hit the limit, they face profile corruption. Sometimes due to a corrupted PST, the profile becomes inaccessible, and it needs repair. One of the many reasons for Outlook profile corruption is a corrupted PST. Try automated tool Kernel for Outlook PST Repair to repair corrupt PST file and fix Outlook PST error issues.
