Despite I run dotnet-dump under root, and process is run under root (see service description below), it seems I lack some permissions.
I tried also other directories in home, in var and in tmp: all the same message.

```
root@DSK06511:/home/monouser# dotnet-dump collect -p 10131 --diag -o /var/tmp/MyNodeDump/
Writing full to /var/tmp/MyNodeDump/
Writing dump failed (HRESULT: 0x80004005)

root@DSK06511:/tmp# dotnet-dump collect -p 10131 --diag -o /home/monorepo/tmp/
Writing full to /home/monouser/tmp/
Writing dump failed (HRESULT: 0x80004005)

```

Service file:

```
root@DSK06511:/home/monouser# cat  /etc/systemd/system/MyNode.service
[Unit]
Description=MyNode

[Service]
Type=simple

User=root
Group=root

ExecStart=/home/monouser/.octopus/Applications/OctopusServer/Production/MyNode.Linux/4.0.1.907/MyNode --console

[Install]
WantedBy=multi-user.target

```

Diagnostics info:
 dotnet-dump --version
 3.1.120604+97218bff6a14e60360862529b09b687789cc1279

```
dotnet --info
.NET Core SDK (reflecting any global.json):
 Version:   3.1.201
 Commit:    b1768b4ae7

Runtime Environment:
 OS Name:     ubuntu
 OS Version:  18.04
 OS Platform: Linux
 RID:         ubuntu.18.04-x64
 Base Path:   /usr/share/dotnet/sdk/3.1.201/

Host (useful for support):
  Version: 3.1.3
  Commit:  4a9f85e9f8

.NET Core SDKs installed:
  3.1.201 [/usr/share/dotnet/sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.App 3.1.3 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 3.1.3 [/usr/share/dotnet/shared/Microsoft.NETCore.App]

```

OS version NAME="Ubuntu" VERSION="18.04.3 LTS (Bionic Beaver)"

They had similar issue [here](https://github.com/dotnet/diagnostics/issues/449) but they solved it with --output to the directory in /tmp, which didn't help