Platform SSO "Page not found" on macOS Tahoe 26.4 — Company Portal 5.2602

I can’t confirm that the URL(filePath:) warning is the root cause, and I don’t see this exact failure listed as a published Platform SSO known issue. The clean-device reproduction makes a client/OS compatibility issue plausible, but I’d first rule out configuration.

For an ADE device with user affinity, assign the Platform SSO policy to a user group, not a device group or filter. If you enable PSSO during Setup Assistant, the Settings Catalog policy, Company Portal app, and ADE enrollment profile should all target the same static user group. Confirm that only one SSO extension payload applies, {{DEVICEREGISTRATION}} is present, and the macOS 14+ authentication method is UserSecureEnclaveKey.

Update Company Portal through Microsoft AutoUpdate so you aren’t redeploying the same 5.2602 package, then capture Company Portal logs after reproduction. If the latest build still fails on clean 26.4 devices, open an Intune support case with those logs and the exported profile. Don’t assume a downgrade or hotfix is supported until Microsoft confirms it.