Thanks for your support RehabMan.
After many attempts I finally installed High Sierra on the laptop. There's just one final issue I have to solve. Every time I boot it up I got the following kernel panic advice:
Anonymous UUID: 0C822CF7-4501-DFB5-4A1B-4D3486328959
Fri Jul 6 15:55:58 2018
*** Panic Report ***
panic(cpu 2 caller 0xffffff7f983eb3b0): assertmsg@/Library/Caches/com.apple.xbs/Sources/GPUDriversIntel/GPUDriversIntel-10.28.29/Common/IONDRV/Intel/KBL/AppleIntelFramebuffer/AppleIntelController.cpp:27160
Backtrace (CPU 2), Frame : Return Address
0xffffff81220a3a80 : 0xffffff801486b6f6
0xffffff81220a3ad0 : 0xffffff8014996f54
0xffffff81220a3b10 : 0xffffff8014988c39
0xffffff81220a3b90 : 0xffffff801481d190
0xffffff81220a3bb0 : 0xffffff801486b1cc
0xffffff81220a3ce0 : 0xffffff801486af4c
0xffffff81220a3d40 : 0xffffff7f983eb3b0
0xffffff81220a3db0 : 0xffffff7f983e7e9b
0xffffff81220a3e40 : 0xffffff8014e7d75d
0xffffff81220a3e80 : 0xffffff8014e7d4a1
0xffffff81220a3f00 : 0xffffff8014e7c9c7
0xffffff81220a3f50 : 0xffffff8014e7e5d6
0xffffff81220a3fa0 : 0xffffff801481a4f7
Kernel Extensions in backtrace:
com.apple.driver.AppleIntelKBLGraphicsFramebuffer(10.2.8)[18F54DD0-5EDA-374E-AAC7-87D132A116C7]@0xffffff7f983c0000->0xffffff7f98594fff
dependency: com.apple.iokit.IOPCIFamily(2.9)[1A5661CA-0F8F-3EC1-B3B4-5A9ADDAE360F]@0xffffff7f950e6000
dependency: com.apple.iokit.IOACPIFamily(1.4)[8794C760-FDD9-3664-ADED-4A9BBEC6E517]@0xffffff7f950dd000
dependency: com.apple.iokit.IOAcceleratorFamily2(374.1)[1A14B541-7F4E-3D7A-B279-43185331BB30]@0xffffff7f98320000
dependency: com.apple.iokit.IOReportFamily(31)[D2F2FBDF-4EE4-38BA-99F5-B699F886F413]@0xffffff7f950d6000
dependency: com.apple.AppleGraphicsDeviceControl(3.16.19)[35BE1077-5D56-3353-BFC5-F6026B931F81]@0xffffff7f983b6000
dependency: com.apple.iokit.IOGraphicsFamily(517.17)[05FC87E8-B78E-319E-AF08-0EBDA16094CE]@0xffffff7f982da000
BSD process name corresponding to current thread: kernel_task
Boot args: dart=0 -disablegfxfirmware root-dmg=file:///Install%20macOS%20High%20Sierra.app/Contents/SharedSupport/BaseSystem.dmg
Mac OS version:
17B48
Kernel version:
Darwin Kernel Version 17.2.0: Fri Sep 29 18:27:05 PDT 2017; root:xnu-4570.20.62~3/RELEASE_X86_64
Kernel UUID: 4B214D53-883B-3E5F-A115-9FDA17E68BA8
Kernel slide: 0x0000000014600000
Kernel text base: 0xffffff8014800000
__HIB text base: 0xffffff8014700000
System model name: iMac18,3 (Mac-BE088AF8C5EB4FA2)
System uptime in nanoseconds: 169986145696
last loaded kext at 169983017216: com.apple.iokit.IONDRVSupport 517.17 (addr 0xffffff7f985df000, size 57344)
loaded kexts:
com.insanelymac.IntelMausiEthernet 2.3.0
as.vit9696.AppleALC 1.2.6
org.tw.CodecCommander 2.6.3
org.netkas.driver.FakeSMC 1765
as.lvs1974.IntelGraphicsFixup 1.2.7
as.vit9696.Shiki 2.2.6
as.vit9696.Lilu 1.2.3
com.apple.driver.AppleIntelPCHPMC 2.0.1
com.apple.driver.AppleIntelSlowAdaptiveClocking 4.0.0
com.apple.driver.AppleFIVRDriver 4.1.0
com.apple.driver.AppleIntelKBLGraphicsFramebuffer 10.2.8
com.apple.driver.AppleOSXWatchdog 1
com.apple.nke.webcontentfilter 5
com.apple.driver.DiskImages.ReadWriteDiskImage 480.1.2
com.apple.driver.DiskImages.SparseDiskImage 480.1.2
com.apple.driver.DiskImages.UDIFDiskImage 480.1.2
com.apple.driver.DiskImages.HTTPBackingStore 480.1.2
com.apple.driver.DiskImages.FileBackingStore 480.1.2
com.apple.driver.DiskImages.RAMBackingStore 480.1.2
com.apple.iokit.SCSITaskUserClient 404.20.1
com.apple.driver.AppleFileSystemDriver 3.0.1
com.apple.filesystems.hfs.kext 407.1.3
com.apple.BootCache 40
com.apple.AppleFSCompression.AppleFSCompressionTypeDataless 1.0.0d1
com.apple.AppleFSCompression.AppleFSCompressionTypeZlib 1.0.0
com.apple.driver.AppleAHCIPort 329
com.apple.driver.AppleRTC 2.0
com.apple.driver.AppleHPET 1.8
com.apple.driver.AppleACPIButtons 6.1
com.apple.driver.AppleSMBIOS 2.1
com.apple.driver.AppleACPIEC 6.1
com.apple.driver.AppleAPIC 1.7
com.apple.nke.applicationfirewall 183
com.apple.security.TMSafetyNet 8
com.apple.security.quarantine 3
com.apple.IOBufferCopyEngineTest 1
com.apple.iokit.IONDRVSupport 517.17
com.apple.driver.IOPlatformPluginFamily 6.0.0d8
com.apple.driver.AppleHDAController 280.12
com.apple.iokit.IOHDAFamily 280.12
com.apple.driver.Apple16X50Serial 3.2
com.apple.iokit.IOSerialFamily 11
com.apple.driver.AppleSMBusPCI 1.0.14d1
com.apple.iokit.IOSlowAdaptiveClockingFamily 1.0.0
com.apple.AppleGraphicsDeviceControl 3.16.19
com.apple.iokit.IOAcceleratorFamily2 374.1
com.apple.iokit.IOGraphicsFamily 517.17
com.apple.iokit.IOSurface 209
com.apple.driver.DiskImages.KernelBacked 480.1.2
com.apple.driver.usb.cdc 5.0.0
com.apple.driver.usb.networking 5.0.0
com.apple.driver.usb.AppleUSBHostCompositeDevice 1.2
com.apple.filesystems.hfs.encodings.kext 1
com.apple.driver.AppleXsanScheme 3
com.apple.iokit.IOAHCIBlockStorage 301.20.1
com.apple.iokit.IOAHCIFamily 288
com.apple.driver.usb.AppleUSBXHCIPCI 1.2
com.apple.driver.usb.AppleUSBXHCI 1.2
com.apple.driver.AppleIntelLpssGspi 3.0.60
com.apple.driver.usb.AppleUSBHostPacketFilter 1.0
com.apple.iokit.IOUSBFamily 900.4.1
com.apple.driver.AppleEFINVRAM 2.1
com.apple.driver.AppleEFIRuntime 2.1
com.apple.iokit.IOHIDFamily 2.0.0
com.apple.iokit.IOSMBusFamily 1.1
com.apple.security.sandbox 300.0
com.apple.kext.AppleMatch 1.0.0d1
com.apple.iokit.IOAudioFamily 206.5
com.apple.vecLib.kext 1.2.0
com.apple.iokit.IOBufferCopyEngineFamily 1
com.apple.driver.AppleKeyStore 2
com.apple.driver.AppleUSBTDM 439.20.7
com.apple.driver.AppleMobileFileIntegrity 1.0.5
com.apple.iokit.IOUSBMassStorageDriver 140
com.apple.iokit.IOSCSIBlockCommandsDevice 404.20.1
com.apple.iokit.IOSCSIArchitectureModelFamily 404.20.1
com.apple.driver.AppleCredentialManager 1.0
com.apple.driver.KernelRelayHost 1
com.apple.driver.AppleSEPManager 1.0.1
com.apple.driver.IOSlaveProcessor 1
com.apple.driver.AppleFDEKeyStore 28.30
com.apple.iokit.IOTimeSyncFamily 600.15
com.apple.iokit.IONetworkingFamily 3.4
com.apple.driver.DiskImages 480.1.2
com.apple.iokit.IOStorageFamily 2.1
com.apple.iokit.IOBluetoothFamily 6.0.1f1
com.apple.iokit.IOUSBHostFamily 1.2
com.apple.driver.usb.AppleUSBCommon 1.0
com.apple.driver.AppleBusPowerController 1.0
com.apple.iokit.IOReportFamily 31
com.apple.driver.AppleACPIPlatform 6.1
com.apple.driver.AppleSMCRTC 1.0
com.apple.driver.AppleSMC 3.1.9
com.apple.iokit.IOPCIFamily 2.9
com.apple.iokit.IOACPIFamily 1.4
com.apple.kec.Libm 1
com.apple.kec.pthread 1
com.apple.kec.corecrypto 1.0
EOF
Model: MacBookPro13,1, BootROM MBP131.0219.B00, 2 processors, Intel Core i7, 2,81 GHz, 8 GB, SMC 2.36f97
Graphics: Intel HD Graphics 520, Intel HD Graphics 520, Built-In
Memory Module: BANK 0/DIMM0, 8 GB, DDR4, 2400 MHz, Samsung, M471A1K43CB1-CRC
Bluetooth: Version 6.0.0f1, 3 services, 19 devices, 1 incoming serial ports
PCI Card: Realtek ALC293 HD Audio, Audio Controller, Built in
Serial ATA Device: SAMSUNG MZ7LN256HCHP-000L7, 256,06 GB
USB Device: USB 3.0 Bus
USB Device: Vendor-Specific Device
USB Device: Integrated Camera
USB Device: Bluetooth HCI
USB Device: STORE N GO
Thunderbolt Bus:
Any suggestion?