dotnet/runtime · critical

OutOfMemory!

Error message

OutOfMemory!

What it means

The Method constructor (method.cpp:52-53) pre-allocates fixed arrays for exception handlers and endfilter offsets (`new COR_ILMETHOD_SECT_EH_CLAUSE_FAT[MAX_EXCEPTIONS]` and `new DWORD[MAX_EXCEPTIONS]`). If either allocation returns NULL, ilasm prints OutOfMemory and returns, leaving the method unable to track exceptions. This is the method-level analogue of error 220.

Source

Thrown at src/coreclr/ilasm/method.cpp:56

    m_FirstDocument = NULL;
    m_HasMultipleDocuments = FALSE;

    // move the PInvoke descriptor (if any) from Assembler
    // (Assembler gets the descriptor BEFORE it calls new Method)
    m_pPInvoke = pAssembler->m_pPInvoke;
    pAssembler->m_pPInvoke = NULL;

    _ASSERTE(pszName);
    if (!pszName) return;

    m_szName = pszName;
    m_dwName = (DWORD)strlen(pszName);

    m_ExceptionList = new COR_ILMETHOD_SECT_EH_CLAUSE_FAT[MAX_EXCEPTIONS];
    m_EndfilterOffsetList = new DWORD[MAX_EXCEPTIONS];
    if((m_ExceptionList==NULL)||(m_EndfilterOffsetList==NULL))
    {
        fprintf(stderr,"\nOutOfMemory!\n");
        return;
    }
    m_dwMaxNumExceptions = MAX_EXCEPTIONS;
    m_dwMaxNumEndfilters = MAX_EXCEPTIONS;

    m_Attr          = Attr;
    if((!strcmp(pszName,COR_CCTOR_METHOD_NAME))||(!strcmp(pszName,COR_CTOR_METHOD_NAME)))
        m_Attr |= mdSpecialName;
    m_fEntryPoint   = FALSE;
    m_fGlobalMethod = FALSE;

    if(pbsSig)
    {
        m_dwMethodCSig = pbsSig->length();
        m_pMethodSig = (COR_SIGNATURE*)(pbsSig->ptr());
        m_pbsMethodSig = pbsSig;
    }

View on GitHub (pinned to 290d5ab72c)

Solutions

1. Free memory on the host or move to a 64-bit ilasm build.
2. Reduce the size of the assembly (fewer methods / split modules).
3. Increase the container/CI memory limit.

Example fix

// before: single huge assembly with tens of thousands of methods
ilasm /out=huge.dll huge.il   # OutOfMemory!
// after: split into smaller modules then merge
ilasm /out=part1.dll part1.il

// Warn before assembling if the module has an extreme method count
// (each Method pre-allocates two fixed arrays).
if (methodCount > 100000) warn('Large method count; ilasm may hit per-method OOM on low-RAM hosts');

When it happens

Trigger: Assembling a file while the process is under severe memory pressure; an extremely large number of methods causing many simultaneous allocations.

Common situations: CI with tight memory limits; assembling a machine-generated assembly with many methods on a 32-bit build.

Related errors

• Out of memory!
• Out of memory!
• Out of memory in Indx256::IndexString!
• Out of memory!
• .NET runtime has failed to start, because too much memory wa

AI-assisted analysis of dotnet/runtime@290d5ab72c (2026-08-06). Data as JSON: /api/errors/175748056d58b5cf. Report an issue: GitHub.