Turn off Windows Defender real-time protection temporarily

• Tamper protection: Microsoft says that if tamper protection is on, you need to turn it off first (same page, further down). Turn it back on afterwards.
• Work or school PC: the IT department may control this setting.
• Another antivirus is installed: Microsoft Defender turns itself off when a compatible third-party antivirus is active. Pause that program instead, using its vendor's instructions.

If Defender keeps blocking one trusted program or folder, add an exclusion instead: on the same Virus & threat protection settings page, under Exclusions, select Add or remove exclusions and choose File, Folder, File type or Process. Excluded items are not scanned in real time, so add only what you trust, and remove the exclusion when you no longer need it.

While real-time protection is off, files you open or download are not scanned. Scheduled scans still run. The firewall is a separate setting and stays on.