customer dependency - spill over
Customer committed that they will send us the necessary files to load into DB.
We created JIRA user stories to load customer data from a file to database. But often customer does not send the files on time and if they send it, the file is not fit for loading so we again ask customer to fix and resend the file.
Due to the above reason 20-30% of the tickets gets spilled over in every sprint as the customer is unable to deliver the correct files on time.
what can I do to minimize the spill over and any other way to handle these scenarios?
A Sprint is not a bucket. Nothing spills over. In Scrum a Sprint Goal is either met or it isn't. The work being done each Sprint is an emerging forecast of what the Developers believe they need to do to meet their Sprint Goal commitment. Are Sprint Goals being framed and met in your situation?
What is your Scrum Master tolerating such impediments to flow efficiency?
In the meantime, in Sprint Planning, if there are dependencies, encourage the team to only pull in the items where the customer has first met the dependency. Otherwise, the PBI can be considered for a future Sprint.
In the Sprint Review your Product Owner can let the customer know that any PBI that is missing the required dependency will get re-ordered lower in the Product Backlog.
The way you described the situation, it seems like you are doing a lot of repeatable tasks to accomplish a specific state over and over again. To me that doesn't sound very complex. Are you sure that Scrum is the correct solution for you? Scrum works best when there are complex problems to solve that have uncertainty built in. With a "20-30% spillover" related to the inability to load data into a DB, you might want to rethink your process.
If you do want to remain with Scrum, then the advice that @Ian and @Chris provide are good places for you to start. Work on crafting better Sprint Goals. Encourage the Developers to pull work into the Sprint for which they feel confident can be completed in the Sprint. If there are still outstanding external dependencies, then as a Developer, I would not feel very confident in the ability to complete that work.