Falling back to limited functionality! Cannot use dub with invalid configuration

[topazus]

I got some trouble with serve-d and dcd in VSCode for the first time, and need some helps. Here are the related logs.

serve-d standalone v0.8.0-beta.7
Included features: "d", "workspaces"
Built: Wed Nov  9 03:04:08 2022
with compiler LDC v2.100 on linux littleEndian
dub, dfmt and dscanner are bundled within (compiled in)
2022-11-10T06:43:49.864 [info] extension.d:477:rootsForProject Root Suggestions: [RootSuggestion("/home/ruby/learn/dlang/learn", true)]
2022-11-10T06:43:49.864 [info] extension.d:509:doStartup registering instance for root RootSuggestion("/home/ruby/learn/dlang/learn", true)
2022-11-10T06:43:49.865 [info] extension.d:599:delayedProjectActivation Initializing instance for root RootSuggestion("/home/ruby/learn/dlang/learn", true)
2022-11-10T06:43:49.903 [error] extension.d:633:delayedProjectActivation Exception starting dub: object.Exception@workspace-d/source/workspaced/com/dub.d(251): Cannot use dub with invalid configuration
----------------
??:? [0x55c41d3935b6]
??:? [0x55c41d394e56]
??:? [0x55c41d37628f]
??:? [0x55c41d09d01b]
??:? [0x55c41cedb5ce]
??:? [0x55c41cedae90]
??:? [0x55c41cefb845]
??:? [0x55c41cefbb89]
??:? [0x55c41ce83b05]
??:? [0x55c41ced5889]
??:? [0x55c41ce6e005]
??:? [0x55c41ce6df61]
??:? [0x55c41ce6da57]
??:? [0x55c41ce6ce53]
??:? [0x55c41cdff127]
??:? [0x55c41cdff9a0]
??:? [0x55c41d36eb9a]
2022-11-10T06:43:49.905 [error] extension.d:641:delayedProjectActivation Failed starting dub in RootSuggestion("/home/ruby/learn/dlang/learn", true) - falling back to fsworkspace
2022-11-10T06:43:49.905 [info] extension.d:670:delayedProjectActivation Root RootSuggestion("/home/ruby/learn/dlang/learn", true) initialized in 39 ms, 926 μs, and 6 hnsecs
2022-11-10T06:43:49.916 [error] serverconfig.d:321:validateConfigurationItemsResponse Got invalid configuration response from language client. (not an array)
2022-11-10T06:43:49.916 [error] serverconfig.d:157:setupConfig_Initialized Syncing user configuration failed!
2022-11-10T06:43:49.916 [error] jsonrpc.d:939:showErrorMessage Error message:  Could not initialize dub for /home/ruby/learn/dlang/learn. Falling back to limited functionality!

Cannot use dub with invalid configuration
{"code":-32600,"message":"unknown request response ID"}
[Trace - 6:46:32 AM] Sending notification '$/setTrace'.
Params: {
    "value": "verbose"
}


2022-11-10T06:46:43.695 [trace] serverbase.d:309:__lambda3 Calling notification method setTrace