Make sure you are not using special characters in file names. 

Before uploading a file to SharePoint, make sure there are no special characters in the file name. The following list of special characters may not be used in file names in OneDrive for Business on Office 365, SharePoint Online:  " # % * : < > ? / \ |

Separate words in file names with underscores or dashes

As a general best practice, use underscores "_" or dashes “-“ between words in file names. For example: Recommended_File_Name.docx. When you use spaces in file names, all of the spaces will be converted to the characters "%20" in hyperlinks, so a document named Recommended Practice File Name would appear in a link as:

http://myportal.com/myteamsite/documents/Recommended%20File%20%Name.docx

Check the properties of Office documents before you upload 

In addition, examine the Properties fields of all Office documents and make sure that if any field (such as Author, Comments, or Title) has any data in it that the content accurately describes the document. If not, delete any values that are not accurate and re-save the document. The value of the Title, Author, and Comments in your documents are automatically added to SharePoint when you upload your document and these fields are used in search results. The Author and Comments fields must be edited in Microsoft Office (Word, PowerPoint, Excel), but you can change the Title for your document in the intranet by editing the document properties. 

Avoid using Dates in file names 

You do not need to use Dates in your file names. Every document has a Created By and Modified By date in the system, so dates are usually not needed as part of the name of a document. All file names must be unique within a folder or library, so you might need to add a date to your file name only if you have two documents that must have the same name and you need to distinguish between the two.

Do not use version numbers in file names 

Don't add version numbers to file names. We have versioning turned on in SharePoint, so if you want to publish an updated version of a document, just upload it with the same name as the previous version and the system will place the new version on top of the old version. Old versions are not found during searches, but you can examine old versions of a document by [[Viewing Version History]].