Short answer
Before migration, check filenames, blocked names and complete destination paths. Then test a representative batch with your migration tool. DNM can help you review names locally; it cannot guarantee a successful migration.
A folder that works on a local drive can encounter different restrictions when it moves to SharePoint or OneDrive. Naming is one part of readiness, alongside permissions, file types, destination structure and the migration tool itself. Use this checklist before moving the full collection.
Step 1: Review characters and spacing
Check files and folders for characters Microsoft restricts, including " * : < > ? / \ |, and remove leading or trailing spaces. Avoid names ending in a period. Many of these are already restricted by Windows; they are not characters that Windows freely accepts but Microsoft 365 suddenly rejects. Start with Microsoft's current restrictions for your environment.
Step 2: Check blocked names and file types
Microsoft lists reserved device names, .lock, desktop.ini, names beginning with ~$ and names containing _vti_ among its restrictions. There are also location-specific rules, such as forms at a library root. Review temporary and system files before migration rather than simply renaming and uploading everything. Your organization may block additional file types.
Step 3: Measure the destination, not just the filename
SharePoint and OneDrive allow up to 400 characters in a decoded service path. A space represented as %20 counts as one decoded character. Windows applications using the conventional MAX_PATH limit have a smaller budget: 260 characters including the terminating null, or up to 259 visible characters. Longer-path support depends on both the application and system configuration.
Check the actual destination folders and local sync root. Individual names and the sync client have additional limits; the path-length guide explains how those fit together. A short filename alone is not proof that the destination path will work.
Step 4: Choose a repeatable naming pattern
Agree on the information a colleague needs to recognize the file: a client or project reference, a document date, a short description and a type. DNM's built-in standards use different field orders. For example, its General standard places the description before the type; the Strata standard places the type before the description.
Choose the appropriate standard, configure the fields and review the proposed names. Consistent structure helps people interpret the files, but user-entered values and destination paths still need checking. See the DNM naming standard or try the naming convention generator.
Step 5: Test a representative migration
Keep a recoverable copy before bulk renaming. Include deep paths, long names and the file types your team actually uses in a test batch. Check the migration report, sync behavior, access permissions and important links or embedded references. Link behavior after a rename depends on the link type and system, so verify it rather than assuming every link will survive or break.
Where DNM fits
DNM is a Windows naming app, not a migration service. Import files or queue them through Watch Folder, review suggested names and common naming warnings, then save the changes you choose. Document naming and supported OCR run locally. Licensing, updates and information you choose to send to support are separate from that document-processing workflow.
For a separate search-time planning exercise, the Cost of File Chaos calculator models a scenario from your inputs. It does not estimate migration failures or migration costs.
Common questions
Will Microsoft 365 fix rejected names during migration?
Behavior depends on the migration tool and its settings. Review its reports and test a sample; do not rely on automatic renaming to preserve references or choose meaningful names.
Does passing DNM's Microsoft 365 check guarantee a successful migration?
No. It checks common naming and path restrictions for the supplied inputs. It is not Microsoft certification and does not validate every migration setting, permission, link or later destination.
Does DNM upload documents to check their names?
No. Naming checks and supported document processing run locally on your Windows PC. Uploading files to Microsoft 365 is a separate step.