Comment 0 for bug 1961829

image: 20.04.4.ga.rc.20220218.1
platform: saber thunderX2

Steps to Reproduce:
1. Boot with PXE
2. Get into subiquity prompt
3. Select rich mode
4. Follow the prompt instruction

Expected Result:
1. installation begins

Actual Result:
I was dropped into subiquity shell on filling the prompt of username and password. By collecting the logs I found:

 2022-02-22 18:06:58,889 ERROR root:39 finish: subiquity/Filesystem/_probe/probe_once: FAIL: Invalid dep_id (disk-dm-0) not in storage config
 2022-02-22 18:06:58,890 ERROR block-discover:433 block probing failed restricted=False
 Traceback (most recent call last):
   File "/snap/subiquity/3095/lib/python3.8/site-packages/subiquity/server/controllers/filesystem.py", line 427, in _probe
     await asyncio.wait_for(self._probe_once_task.task, 15.0)
   File "/snap/subiquity/3095/usr/lib/python3.8/asyncio/tasks.py", line 494, in wait_for
     return fut.result()
   File "/snap/subiquity/3095/lib/python3.8/site-packages/subiquitycore/context.py", line 148, in decorated_async
     return await meth(self, **kw)
   File "/snap/subiquity/3095/lib/python3.8/site-packages/subiquity/server/controllers/filesystem.py", line 412, in _probe_once
     self.model.load_probe_data(storage)
   File "/snap/subiquity/3095/lib/python3.8/site-packages/subiquity/models/filesystem.py", line 1287, in load_probe_data
     self.reset()
   File "/snap/subiquity/3095/lib/python3.8/site-packages/subiquity/models/filesystem.py", line 965, in reset
     self._orig_config = storage_config.extract_storage_config(
   File "/snap/subiquity/3095/lib/python3.8/site-packages/curtin/storage_config.py", line 1346, in extract_storage_config
     tree = get_config_tree(cfg.get('id'), final_config)
   File "/snap/subiquity/3095/lib/python3.8/site-packages/curtin/storage_config.py", line 306, in get_config_tree
     for dep in find_item_dependencies(item, sconfig):
   File "/snap/subiquity/3095/lib/python3.8/site-packages/curtin/storage_config.py", line 276, in find_item_dependencies
     _validate_dep_type(item_id, dep_key, dep, config)
   File "/snap/subiquity/3095/lib/python3.8/site-packages/curtin/storage_config.py", line 223, in _validate_dep_type
     raise ValueError(
 ValueError: Invalid dep_id (disk-dm-0) not in storage config