Server restart loop, all up to date after a fresh install

[uMod] 06:06 PM [Warning] Valheim server up to date (6950213). Use --force to update from the depot anyway
[uMod] 06:06 PM [Warning] Valheim already up to date (v1.0.308-develop)
[uMod] 06:06 PM [Warning] uMod WebClient already up to date (v1.0.356-develop)
[uMod] 06:06 PM [Warning] uMod Compiler already up to date (v1.0.511-develop)
[uMod] 06:06 PM [Warning] uMod Database already up to date (v1.0.400-develop)
Starting server...

Set current directory to /home/uval
Found path: /home/uval/valheim_server.x86_64
Mono path[0] = '/home/uval/valheim_server_Data/Managed'
Mono config path = '/home/uval/valheim_server_Data/MonoBleedingEdge/etc'
Preloaded ''
Initialize engine version: 2019.4.24f1 (5da6f0345e82)
[Subsystems] Discovering subsystems at path /home/uval/valheim_server_Data/UnitySubsystems
Forcing GfxDevice: Null
GfxDevice: creating device client; threaded=0
Version: NULL 1.0 [1.0]
Renderer: Null Device
Vendor: Unity Technologies
Begin MonoManager ReloadAssembly
Unable to find method IsLoggingEnabled in [UnityEngine.CoreModule.dll]UnityEngine.Debug
(Filename: Line: 143)

Caught fatal signal - signo:11 code:1 errno:0 addr:(nil)
Obtained 21 stack frames.
#0 0x007fa7ec33f3c0 in funlockfile
#1 0x007fa7eb9fbfbb in mono_print_method_from_ip
#2 0x007fa7ebb6c37c in mono_perfcounter_foreach
#3 0x007fa7ebb6d229 in mono_runtime_invoke
#4 0x007fa7ecece642 in scripting_method_invoke(ScriptingMethodPtr, ScriptingObjectPtr, ScriptingArguments&, ScriptingExceptionPtr*, bool)
#5 0x007fa7ececc9da in ScriptingInvocation::Invoke(ScriptingExceptionPtr*, bool)
#6 0x007fa7ececc91c in bool ScriptingInvocation::Invoke<bool>(ScriptingExceptionPtr*, bool)
#7 0x007fa7ec717dd7 in Scripting::UnityEngine::DebugProxy::IsLoggingEnabled(ScriptingExceptionPtr*)
#8 0x007fa7ececca3b in ScriptingInvocation::Invoke(ScriptingExceptionPtr*, bool)
#9 0x007fa7eceb69b9 in MonoManager::LoadAssemblies(dynamic_bitset)
#10 0x007fa7eceb6fe8 in MonoManager::BeginReloadAssembly(DomainReloadingData&)
#11 0x007fa7eceb595f in MonoManager::ReloadAssembly()
#12 0x007fa7ecf17509 in AwakeFromLoadQueue::InvokePersistentManagerAwake(AwakeFromLoadQueue::Item*, unsigned int, AwakeFromLoadMode)
#13 0x007fa7ecf16e30 in AwakeFromLoadQueue::PersistentManagerAwakeFromLoad()
#14 0x007fa7ecf04053 in PersistentManager::LoadAndIntegrateAllPreallocatedObjects(PersistentManager::LockFlags)
#15 0x007fa7ecf0466b in PersistentManager::ReadObject(int, AwakeFromLoadMode)
#16 0x007fa7ecb9bfa1 in PlayerLoadGlobalManagers(char const*, char const*, unsigned int)
#17 0x007fa7ecdbfb71 in PlayerInitEngineGraphics(bool)
#18 0x007fa7ecf24919 in PlayerMain(int, char**)
#19 0x007fa7ec15f0b3 in __libc_start_main
#20 0x0055cba6fab699 in _start
Server closed unexpectedly...

Restarting server...

The error indicates that you are using an older build somehow, at least in part. Please try updating with the --force option as it suggests.