NIOS V Sysnthesis Fails with Quartus 25.1 Lite

Hi,

I used Quartus 23.1 Lite for a couple of months and have now switched to Quartus 25.1 Lite. Since the version update my NIOS V Plattform Designer Projects do not synthesize any longer.

Synthesis fails with:

Info (12128): Elaborating entity "niosv" for hierarchy "niosv:u0"
Info (12128): Elaborating entity "niosv_intel_niosv_m_0" for hierarchy "niosv:u0|niosv_intel_niosv_m_0:intel_niosv_m_0"
Info (12128): Elaborating entity "niosv_intel_niosv_m_0_hart" for hierarchy "niosv:u0|niosv_intel_niosv_m_0:intel_niosv_m_0|niosv_intel_niosv_m_0_hart:hart"
Error (10835): SystemVerilog error at riscv.pkg.sv(149): no support for unions
Error (10835): SystemVerilog error at riscv.pkg.sv(333): no support for unions
Error (10355): SystemVerilog Enumeration Type Declaration error at riscv.pkg.sv(1163): encoded value for element "MXL32" has width 32, which does not match the width of the enumeration's base type (2)
Error (10355): SystemVerilog Enumeration Type Declaration error at riscv.pkg.sv(1164): encoded value for element "MXL64" has width 32, which does not match the width of the enumeration's base type (2)
Error (10355): SystemVerilog Enumeration Type Declaration error at riscv.pkg.sv(1165): encoded value for element "MXL128" has width 32, which does not match the width of the enumeration's base type (2)
Error (10355): SystemVerilog Enumeration Type Declaration error at riscv.pkg.sv(1167): encoded value for element "MXL_RESERVED" has width 32, which does not match the width of the enumeration's base type (2)
Error (10355): SystemVerilog Enumeration Type Declaration error at riscv.pkg.sv(1233): encoded value for element "INSTRUCTION_MISALIGNED" has width 32, which does not match the width of the enumeration's base type (5)
Error (10355): SystemVerilog Enumeration Type Declaration error at riscv.pkg.sv(1234): encoded value for element "INSTRUCTION_ACCESS_FAULT" has width 32, which does not match the width of the enumeration's base type (5)
Error (10355): SystemVerilog Enumeration Type Declaration error at riscv.pkg.sv(1235): encoded value for element "ILLEGAL_INSTRUCTION" has width 32, which does not match the width of the enumeration's base type (5)
Error (10355): SystemVerilog Enumeration Type Declaration error at riscv.pkg.sv(1236): encoded value for element "BREAKPOINT" has width 32, which does not match the width of the enumeration's base type (5)
Error (10355): SystemVerilog Enumeration Type Declaration error at riscv.pkg.sv(1237): encoded value for element "LOAD_ADDRESS_MISALIGNED" has width 32, which does not match the width of the enumeration's base type (5)
Error (10355): SystemVerilog Enumeration Type Declaration error at riscv.pkg.sv(1238): encoded value for element "LOAD_ACCESS_FAULT" has width 32, which does not match the width of the enumeration's base type (5)
Error (10355): SystemVerilog Enumeration Type Declaration error at riscv.pkg.sv(1239): encoded value for element "STORE_AMO_ADDRESS_MISALIGNED" has width 32, which does not match the width of the enumeration's base type (5)
Error (10355): SystemVerilog Enumeration Type Declaration error at riscv.pkg.sv(1240): encoded value for element "STORE_AMO_ACCESS_FAULT" has width 32, which does not match the width of the enumeration's base type (5)
Error (10355): SystemVerilog Enumeration Type Declaration error at riscv.pkg.sv(1241): encoded value for element "USER_ECALL" has width 32, which does not match the width of the enumeration's base type (5)
Error (10355): SystemVerilog Enumeration Type Declaration error at riscv.pkg.sv(1242): encoded value for element "SUPERVISOR_ECALL" has width 32, which does not match the width of the enumeration's base type (5)
Error (10355): SystemVerilog Enumeration Type Declaration error at riscv.pkg.sv(1243): encoded value for element "MACHINE_ECALL" has width 32, which does not match the width of the enumeration's base type (5)
Error (10355): SystemVerilog Enumeration Type Declaration error at riscv.pkg.sv(1244): encoded value for element "INSTRUCTION_PAGE_FAULT" has width 32, which does not match the width of the enumeration's base type (5)
Error (10355): SystemVerilog Enumeration Type Declaration error at riscv.pkg.sv(1245): encoded value for element "LOAD_PAGE_FAULT" has width 32, which does not match the width of the enumeration's base type (5)
Error (12152): Can't elaborate user hierarchy "niosv:u0|niosv_intel_niosv_m_0:intel_niosv_m_0|niosv_intel_niosv_m_0_hart:hart"
Info (144001): Generated suppressed messages file /home/simon/Documents/QuartusPrime/MAX10_InternalFlash_Ticket/output_files/MAX10_InternalFlash_Ticket.map.smsg
Error: Quartus Prime Analysis & Synthesis was unsuccessful. 20 errors, 30 warnings
    Error: Peak virtual memory: 369 megabytes
    Error: Processing ended: Mon Nov 10 09:24:51 2025
    Error: Elapsed time: 00:00:39
    Error: Total CPU time (on all processors): 00:01:41
Error (293001): Quartus Prime Full Compilation was unsuccessful. 22 errors, 30 warnings

I am using the DE10-Lite Board with the Golden Top example Design and add a very basic Nios V to it.

//=======================================================
//  Structural coding
//=======================================================
    niosv u0 (
        .clk_clk       (MAX10_CLK1_50),       //   clk.clk
        .reset_reset_n (1'b1)  // reset.reset_n
    );

Any idead how I can fix that Issue?

Best regards

Simon