Quick Answer
SAM.gov shows "Entity Validation Failed" or "No Match Found" when its Entity Validation Service can't match the legal name and address you entered against outside records like the IRS and your state's business filings. The most common causes are small formatting differences, a too-new EIN, or an address the system misreads as a duplicate. Your registration stays blocked until the mismatch is corrected or a Federal Service Desk ticket resolves it with the right documentation.