Troubleshooting "Unresolved" types in a snapshot created from a process dump


When importing a process memory dump into dotMemory, the resulting snapshot might contain a lot of “Unresolved” type items:


The process memory dump misses memory segments of specific modules.


dotMemory will automatically attempt to download the missing data from the Microsoft Symbol Server. However, this applies only to system modules. If the dotMemory snapshot misses a significant number of user types, try collecting the process dump with alternative methods, for example:

  1. Get a full core dump using the dotnet-dump tool.
  • Install the dotnet-dump tool by running:
    dotnet tool install -g dotnet-dump
  • To get a full core dump, run:
    dotnet-dump collect --type=Full -o ~/dumps/coredump -p <PID>
  1. Get a full core dump using the createdump tool.
    The createdump tool is included into the .NET runtime installation. To get a process dump, run:
    /usr/share/dotnet/shared/Microsoft.NETCore.App/<vN>/createdump -u -f /tmp/coredump <pid>
  1. Set /proc/<PID>/coredump_filter to “0x3f” to capture more modules
    If the previous tools still generate dumps with unresolved modules, try the following workaround to get a more complete list of modules:
    • Open a terminal and edit the coredump_filter file:
      echo"0x3f" > /proc/<PID>/coredump_filter
    • Verify that the value is applied correctly:
    • Get a process dump from the same terminal instance.
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