[Bug]: External storage failing on some shares

[oculos]

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

I have installed 29 Beta 4. I got this problem with a few shares on External storage:

{"reqId":"1Adn4gWfs1DGF0ZLhMbM","level":2,"time":"2024-03-20T18:02:48+00:00","remoteAddr":"","user":"--","app":"no app in context","method":"","url":"--","message":"External storage not available: Invalid request for / (ForbiddenException)","userAgent":"--","version":"29.0.0.11","exception":{"Exception":"OCP\\Files\\ForbiddenException","Message":"Invalid request for / (ForbiddenException)","Code":0,"Trace":[{"file":"/var/www/nextcloud/apps/files_external/lib/Lib/Storage/SMB.php","line":368,"function":"getFileInfo","class":"OCA\\Files_External\\Lib\\Storage\\SMB","type":"->"},{"file":"/var/www/nextcloud/lib/private/Files/Storage/Common.php","line":470,"function":"stat","class":"OCA\\Files_External\\Lib\\Storage\\SMB","type":"->"},{"file":"/var/www/nextcloud/apps/files_external/lib/Lib/Storage/SMB.php","line":760,"function":"test","class":"OC\\Files\\Storage\\Common","type":"->"},{"file":"/var/www/nextcloud/apps/files_external/lib/Command/StorageAuthBase.php","line":117,"function":"test","class":"OCA\\Files_External\\Lib\\Storage\\SMB","type":"->"},{"file":"/var/www/nextcloud/apps/files_external/lib/Command/Scan.php","line":76,"function":"createStorage","class":"OCA\\Files_External\\Command\\StorageAuthBase","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"/var/www/nextcloud/3rdparty/symfony/console/Command/Command.php","line":298,"function":"execute","class":"OCA\\Files_External\\Command\\Scan","type":"->"},{"file":"/var/www/nextcloud/core/Command/Base.php","line":177,"function":"run","class":"Symfony\\Component\\Console\\Command\\Command","type":"->"},{"file":"/var/www/nextcloud/3rdparty/symfony/console/Application.php","line":1040,"function":"run","class":"OC\\Core\\Command\\Base","type":"->"},{"file":"/var/www/nextcloud/3rdparty/symfony/console/Application.php","line":301,"function":"doRunCommand","class":"Symfony\\Component\\Console\\Application","type":"->"},{"file":"/var/www/nextcloud/3rdparty/symfony/console/Application.php","line":171,"function":"doRun","class":"Symfony\\Component\\Console\\Application","type":"->"},{"file":"/var/www/nextcloud/lib/private/Console/Application.php","line":213,"function":"run","class":"Symfony\\Component\\Console\\Application","type":"->"},{"file":"/var/www/nextcloud/console.php","line":113,"function":"run","class":"OC\\Console\\Application","type":"->"},{"file":"/var/www/nextcloud/occ","line":11,"args":["/var/www/nextcloud/console.php"],"function":"require_once"}],"File":"/var/www/nextcloud/apps/files_external/lib/Lib/Storage/SMB.php","Line":215,"Previous":{"Exception":"Icewind\\SMB\\Exception\\ForbiddenException","Message":"Invalid request for / (ForbiddenException)","Code":13,"Trace":[{"file":"/var/www/nextcloud/apps/files_external/3rdparty/icewind/smb/src/Native/NativeState.php","line":75,"function":"fromMap","class":"Icewind\\SMB\\Exception\\Exception","type":"::"},{"file":"/var/www/nextcloud/apps/files_external/3rdparty/icewind/smb/src/Native/NativeState.php","line":92,"function":"handleError","class":"Icewind\\SMB\\Native\\NativeState","type":"->"},{"file":"/var/www/nextcloud/apps/files_external/3rdparty/icewind/smb/src/Native/NativeState.php","line":351,"function":"testResult","class":"Icewind\\SMB\\Native\\NativeState","type":"->"},{"file":"/var/www/nextcloud/apps/files_external/3rdparty/icewind/smb/src/Native/NativeShare.php","line":305,"function":"getxattr","class":"Icewind\\SMB\\Native\\NativeState","type":"->"},{"file":"/var/www/nextcloud/apps/files_external/3rdparty/icewind/smb/src/Native/NativeFileInfo.php","line":43,"function":"getAttribute","class":"Icewind\\SMB\\Native\\NativeShare","type":"->"},{"file":"/var/www/nextcloud/apps/files_external/3rdparty/icewind/smb/src/Native/NativeFileInfo.php","line":69,"function":"stat","class":"Icewind\\SMB\\Native\\NativeFileInfo","type":"->"},{"file":"/var/www/nextcloud/apps/files_external/3rdparty/icewind/smb/src/Native/NativeShare.php","line":114,"function":"getSize","class":"Icewind\\SMB\\Native\\NativeFileInfo","type":"->"},{"file":"/var/www/nextcloud/apps/files_external/lib/Lib/Storage/SMB.php","line":201,"function":"stat","class":"Icewind\\SMB\\Native\\NativeShare","type":"->"},{"file":"/var/www/nextcloud/apps/files_external/lib/Lib/Storage/SMB.php","line":368,"function":"getFileInfo","class":"OCA\\Files_External\\Lib\\Storage\\SMB","type":"->"},{"file":"/var/www/nextcloud/lib/private/Files/Storage/Common.php","line":470,"function":"stat","class":"OCA\\Files_External\\Lib\\Storage\\SMB","type":"->"},{"file":"/var/www/nextcloud/apps/files_external/lib/Lib/Storage/SMB.php","line":760,"function":"test","class":"OC\\Files\\Storage\\Common","type":"->"},{"file":"/var/www/nextcloud/apps/files_external/lib/Command/StorageAuthBase.php","line":117,"function":"test","class":"OCA\\Files_External\\Lib\\Storage\\SMB","type":"->"},{"file":"/var/www/nextcloud/apps/files_external/lib/Command/Scan.php","line":76,"function":"createStorage","class":"OCA\\Files_External\\Command\\StorageAuthBase","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"/var/www/nextcloud/3rdparty/symfony/console/Command/Command.php","line":298,"function":"execute","class":"OCA\\Files_External\\Command\\Scan","type":"->"},{"file":"/var/www/nextcloud/core/Command/Base.php","line":177,"function":"run","class":"Symfony\\Component\\Console\\Command\\Command","type":"->"},{"file":"/var/www/nextcloud/3rdparty/symfony/console/Application.php","line":1040,"function":"run","class":"OC\\Core\\Command\\Base","type":"->"},{"file":"/var/www/nextcloud/3rdparty/symfony/console/Application.php","line":301,"function":"doRunCommand","class":"Symfony\\Component\\Console\\Application","type":"->"},{"file":"/var/www/nextcloud/3rdparty/symfony/console/Application.php","line":171,"function":"doRun","class":"Symfony\\Component\\Console\\Application","type":"->"},{"file":"/var/www/nextcloud/lib/private/Console/Application.php","line":213,"function":"run","class":"Symfony\\Component\\Console\\Application","type":"->"},{"file":"/var/www/nextcloud/console.php","line":113,"function":"run","class":"OC\\Console\\Application","type":"->"},{"file":"/var/www/nextcloud/occ","line":11,"args":["/var/www/nextcloud/console.php"],"function":"require_once"}],"File":"/var/www/nextcloud/apps/files_external/3rdparty/icewind/smb/src/Exception/Exception.php","Line":44},"message":"External storage not available: Invalid request for / (ForbiddenException)","exception":{},"CustomMessage":"External storage not available: Invalid request for / (ForbiddenException)"}}

Steps to reproduce

1. Open an external storage folder
2. No file is shown
3. Log is full of errors

Expected behavior

To get the share mounted

Installation method

Community Docker image

Nextcloud Server version

master

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.1

Web server

Nginx

Database engine version

MySQL

Is this bug present after an update or on a fresh install?

Updated from a MINOR version (ex. 22.1 to 22.2)

Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

No response

List of activated Apps

No response

Nextcloud Signing status

No response

Nextcloud Logs

No response

Additional info

No response

[joshtrichards]

Your report says you upgraded from a minor version, but this was a beta of 29.0.0.

Was this same Nextcloud Server using this SMB mount previously?

Was this a previously functioning 28.0.x Server that you upgraded to the beta? Or was it working in an earlier 29.0.0 beta?

Just trying to figure out when this broke for you.

[oculos]

Your report says you upgraded from a minor version, but this was a beta of 29.0.0.

Was this same Nextcloud Server using this SMB mount previously?

Was this a previously functioning 28.0.x Server that you upgraded to the beta? Or was it working in an earlier 29.0.0 beta?

Just trying to figure out when this broke for you.

I can't say precisely. It was for sure working on 28.0.X
I noticed it wasn't working on 29.0.2. I upgraded to 29.0.4 to see if it was working again, but nope.

[nextcloud-command]

This issue has been automatically marked as stale because it has not had recent activity and seems to be missing some essential information. It will be closed if no further activity occurs. Thank you for your contributions.

[thomasmerz]

I'm running very latest Nextcloud Hub 10 (31.0.4) and I also have this problem when uploading something to my Nextcloud:

Details
[🇩🇪 -nbg] root@ubuntu-cx11-02:/var/lib/docker/volumes/nextcloud-docker-compose_nextcloud/_data/data # ack "Storage with mount .*is not available" next|tail -1|jq . -r
{
  "reqId": "E8zRshIdXW5nMAdkXNqF",
  "level": 3,
  "time": "2025-05-09T07:59:59+00:00",
  "remoteAddr": "172.23.0.2",
  "user": "thomas",
  "app": "webdav",
  "method": "PROPFIND",
  "url": "/remote.php/dav/files/thomas/My%20Uploads/cloudbeats.cbbackup",
  "message": "Storage with mount id 27 is not available",
  "userAgent": "Mozilla/5.0 (iOS) Nextcloud-iOS/6.6.2",
  "version": "31.0.4.1",
  "exception": {
    "Exception": "Sabre\\DAV\\Exception\\ServiceUnavailable",
    "Message": "Storage with mount id 27 is not available",
    "Code": 0,
    "Trace": [
      {
        "file": "/var/www/html/3rdparty/sabre/dav/lib/DAV/Tree.php",
        "line": 95,
        "function": "getChild",
        "class": "OCA\\DAV\\Connector\\Sabre\\Directory",
        "type": "->",
        "args": [
          "My Uploads"
        ]
      },
      {
        "file": "/var/www/html/3rdparty/sabre/dav/lib/DAV/Server.php",
        "line": 971,
        "function": "getNodeForPath",
        "class": "Sabre\\DAV\\Tree",
        "type": "->",
        "args": [
          "files/thomas/My Uploads/cloudbeats.cbbackup"
        ]
      },
      {
        "file": "/var/www/html/3rdparty/sabre/dav/lib/DAV/Server.php",
        "line": 1664,
        "function": "getPropertiesIteratorForPath",
        "class": "Sabre\\DAV\\Server",
        "type": "->",
        "args": [
          "files/thomas/My Uploads/cloudbeats.cbbackup",
          [
            "{DAV:}displayname",
            "{http://nextcloud.org/ns}share-download-limits",
            "{DAV:}getlastmodified",
            "{DAV:}getetag",
            "{DAV:}getcontenttype",
            "And 42 more entries, set log level to debug to see all entries"
          ],
          0
        ]
      },
      {
        "file": "/var/www/html/3rdparty/sabre/dav/lib/DAV/Server.php",
        "line": 1649,
        "function": "writeMultiStatus",
        "class": "Sabre\\DAV\\Server",
        "type": "->",
        "args": [
          {
            "__class__": "Sabre\\Xml\\Writer",
            "elementMap": [],
            "contextUri": "/remote.php/dav/",
            "namespaceMap": {
              "DAV:": "d",
              "http://sabredav.org/ns": "s",
              "http://owncloud.org/ns": "oc",
              "http://nextcloud.org/ns": "nc"
            },
            "classMap": []
          },
          {
            "__class__": "Generator"
          },
          false
        ]
      },
      {
        "file": "/var/www/html/3rdparty/sabre/dav/lib/DAV/CorePlugin.php",
        "line": 346,
        "function": "generateMultiStatus",
        "class": "Sabre\\DAV\\Server",
        "type": "->",
        "args": [
          {
            "__class__": "Generator"
          },
          false
        ]
      },
      {
        "file": "/var/www/html/3rdparty/sabre/event/lib/WildcardEmitterTrait.php",
        "line": 89,
        "function": "httpPropFind",
        "class": "Sabre\\DAV\\CorePlugin",
        "type": "->",
        "args": [
          {
            "__class__": "Sabre\\HTTP\\Request"
          },
          {
            "__class__": "Sabre\\HTTP\\Response"
          }
        ]
      },
      {
        "file": "/var/www/html/3rdparty/sabre/dav/lib/DAV/Server.php",
        "line": 472,
        "function": "emit",
        "class": "Sabre\\DAV\\Server",
        "type": "->",
        "args": [
          "method:PROPFIND",
          [
            {
              "__class__": "Sabre\\HTTP\\Request"
            },
            {
              "__class__": "Sabre\\HTTP\\Response"
            }
          ]
        ]
      },
      {
        "file": "/var/www/html/apps/dav/lib/Connector/Sabre/Server.php",
        "line": 49,
        "function": "invokeMethod",
        "class": "Sabre\\DAV\\Server",
        "type": "->",
        "args": [
          {
            "__class__": "Sabre\\HTTP\\Request"
          },
          {
            "__class__": "Sabre\\HTTP\\Response"
          }
        ]
      },
      {
        "file": "/var/www/html/apps/dav/lib/Server.php",
        "line": 398,
        "function": "start",
        "class": "OCA\\DAV\\Connector\\Sabre\\Server",
        "type": "->",
        "args": []
      },
      {
        "file": "/var/www/html/apps/dav/appinfo/v2/remote.php",
        "line": 21,
        "function": "exec",
        "class": "OCA\\DAV\\Server",
        "type": "->",
        "args": []
      },
      {
        "file": "/var/www/html/remote.php",
        "line": 145,
        "args": [
          "/var/www/html/apps/dav/appinfo/v2/remote.php"
        ],
        "function": "require_once"
      }
    ],
    "File": "/var/www/html/apps/dav/lib/Connector/Sabre/Directory.php",
    "Line": 185,
    "Previous": {
      "Exception": "OCP\\Files\\StorageNotAvailableException",
      "Message": "Storage with mount id 27 is not available",
      "Code": 1,
      "Trace": [
        {
          "file": "/var/www/html/lib/private/Files/Storage/Wrapper/Wrapper.php",
          "line": 298,
          "function": "acquireLock",
          "class": "OC\\Files\\Storage\\FailedStorage",
          "type": "->",
          "args": [
            "",
            1,
            {
              "__class__": "OC\\Lock\\MemcacheLockingProvider"
            }
          ]
        },
        {
          "file": "/var/www/html/lib/private/Files/Storage/Wrapper/Wrapper.php",
          "line": 298,
          "function": "acquireLock",
          "class": "OC\\Files\\Storage\\Wrapper\\Wrapper",
          "type": "->",
          "args": [
            "",
            1,
            {
              "__class__": "OC\\Lock\\MemcacheLockingProvider"
            }
          ]
        },
        {
          "file": "/var/www/html/lib/private/Files/View.php",
          "line": 2056,
          "function": "acquireLock",
          "class": "OC\\Files\\Storage\\Wrapper\\Wrapper",
          "type": "->",
          "args": [
            "",
            1,
            {
              "__class__": "OC\\Lock\\MemcacheLockingProvider"
            }
          ]
        },
        {
          "file": "/var/www/html/lib/private/Files/View.php",
          "line": 2161,
          "function": "lockPath",
          "class": "OC\\Files\\View",
          "type": "->",
          "args": [
            "//My Uploads",
            1,
            false
          ]
        },
        {
          "file": "/var/www/html/lib/private/Files/View.php",
          "line": 1389,
          "function": "lockFile",
          "class": "OC\\Files\\View",
          "type": "->",
          "args": [
            "//My Uploads",
            1
          ]
        },
        {
          "file": "/var/www/html/lib/private/Files/View.php",
          "line": 1422,
          "function": "getCacheEntry",
          "class": "OC\\Files\\View",
          "type": "->",
          "args": [
            {
              "__class__": "OCA\\Files_Trashbin\\Storage",
              "cache": null,
              "scanner": {
                "__class__": "OC\\Files\\Cache\\Scanner"
              },
              "watcher": null,
              "propagator": null,
              "updater": null
            },
            "",
            "//My Uploads"
          ]
        },
        {
          "file": "/var/www/html/apps/dav/lib/Connector/Sabre/Directory.php",
          "line": 183,
          "function": "getFileInfo",
          "class": "OC\\Files\\View",
          "type": "->",
          "args": [
            "/thomas/files/My Uploads"
          ]
        },
        {
          "file": "/var/www/html/3rdparty/sabre/dav/lib/DAV/Tree.php",
          "line": 95,
          "function": "getChild",
          "class": "OCA\\DAV\\Connector\\Sabre\\Directory",
          "type": "->",
          "args": [
            "My Uploads"
          ]
        },
        {
          "file": "/var/www/html/3rdparty/sabre/dav/lib/DAV/Server.php",
          "line": 971,
          "function": "getNodeForPath",
          "class": "Sabre\\DAV\\Tree",
          "type": "->",
          "args": [
            "files/thomas/My Uploads/cloudbeats.cbbackup"
          ]
        },
        {
          "file": "/var/www/html/3rdparty/sabre/dav/lib/DAV/Server.php",
          "line": 1664,
          "function": "getPropertiesIteratorForPath",
          "class": "Sabre\\DAV\\Server",
          "type": "->",
          "args": [
            "files/thomas/My Uploads/cloudbeats.cbbackup",
            [
              "{DAV:}displayname",
              "{http://nextcloud.org/ns}share-download-limits",
              "{DAV:}getlastmodified",
              "{DAV:}getetag",
              "{DAV:}getcontenttype",
              "And 42 more entries, set log level to debug to see all entries"
            ],
            0
          ]
        },
        {
          "file": "/var/www/html/3rdparty/sabre/dav/lib/DAV/Server.php",
          "line": 1649,
          "function": "writeMultiStatus",
          "class": "Sabre\\DAV\\Server",
          "type": "->",
          "args": [
            {
              "__class__": "Sabre\\Xml\\Writer",
              "elementMap": [],
              "contextUri": "/remote.php/dav/",
              "namespaceMap": {
                "DAV:": "d",
                "http://sabredav.org/ns": "s",
                "http://owncloud.org/ns": "oc",
                "http://nextcloud.org/ns": "nc"
              },
              "classMap": []
            },
            {
              "__class__": "Generator"
            },
            false
          ]
        },
        {
          "file": "/var/www/html/3rdparty/sabre/dav/lib/DAV/CorePlugin.php",
          "line": 346,
          "function": "generateMultiStatus",
          "class": "Sabre\\DAV\\Server",
          "type": "->",
          "args": [
            {
              "__class__": "Generator"
            },
            false
          ]
        },
        {
          "file": "/var/www/html/3rdparty/sabre/event/lib/WildcardEmitterTrait.php",
          "line": 89,
          "function": "httpPropFind",
          "class": "Sabre\\DAV\\CorePlugin",
          "type": "->",
          "args": [
            {
              "__class__": "Sabre\\HTTP\\Request"
            },
            {
              "__class__": "Sabre\\HTTP\\Response"
            }
          ]
        },
        {
          "file": "/var/www/html/3rdparty/sabre/dav/lib/DAV/Server.php",
          "line": 472,
          "function": "emit",
          "class": "Sabre\\DAV\\Server",
          "type": "->",
          "args": [
            "method:PROPFIND",
            [
              {
                "__class__": "Sabre\\HTTP\\Request"
              },
              {
                "__class__": "Sabre\\HTTP\\Response"
              }
            ]
          ]
        },
        {
          "file": "/var/www/html/apps/dav/lib/Connector/Sabre/Server.php",
          "line": 49,
          "function": "invokeMethod",
          "class": "Sabre\\DAV\\Server",
          "type": "->",
          "args": [
            {
              "__class__": "Sabre\\HTTP\\Request"
            },
            {
              "__class__": "Sabre\\HTTP\\Response"
            }
          ]
        },
        {
          "file": "/var/www/html/apps/dav/lib/Server.php",
          "line": 398,
          "function": "start",
          "class": "OCA\\DAV\\Connector\\Sabre\\Server",
          "type": "->",
          "args": []
        },
        {
          "file": "/var/www/html/apps/dav/appinfo/v2/remote.php",
          "line": 21,
          "function": "exec",
          "class": "OCA\\DAV\\Server",
          "type": "->",
          "args": []
        },
        {
          "file": "/var/www/html/remote.php",
          "line": 145,
          "args": [
            "/var/www/html/apps/dav/appinfo/v2/remote.php"
          ],
          "function": "require_once"
        }
      ],
      "File": "/var/www/html/lib/private/Files/Storage/FailedStorage.php",
      "Line": 169,
      "Hint": "Storage is temporarily not available",
      "Previous": {
        "Exception": "OCP\\Files\\StorageNotAvailableException",
        "Message": "Storage with mount id 27 is not available",
        "Code": 1,
        "Trace": [
          {
            "function": "OCA\\Files_External\\Config\\{closure}",
            "class": "OCA\\Files_External\\Config\\ConfigAdapter",
            "type": "->",
            "args": [
              "*** sensitive parameters replaced ***"
            ]
          },
          {
            "file": "/var/www/html/apps/files_external/lib/Config/ConfigAdapter.php",
            "line": 110,
            "function": "array_map",
            "args": [
              {
                "__class__": "Closure"
              },
              [
                "*** sensitive parameters replaced ***",
                "*** sensitive parameters replaced ***",
                "*** sensitive parameters replaced ***",
                "*** sensitive parameters replaced ***",
                "*** sensitive parameters replaced ***",
                "And 5 more entries, set log level to debug to see all entries"
              ],
              [
                "*** sensitive parameters replaced ***",
                "*** sensitive parameters replaced ***",
                "*** sensitive parameters replaced ***",
                "*** sensitive parameters replaced ***",
                "*** sensitive parameters replaced ***",
                "And 5 more entries, set log level to debug to see all entries"
              ]
            ]
          },
          {
            "file": "/var/www/html/lib/private/Files/Config/MountProviderCollection.php",
            "line": 72,
            "function": "getMountsForUser",
            "class": "OCA\\Files_External\\Config\\ConfigAdapter",
            "type": "->",
            "args": [
              {
                "__class__": "OC\\User\\User"
              },
              {
                "__class__": "OC\\Files\\Storage\\StorageFactory"
              }
            ]
          },
          {
            "file": "/var/www/html/lib/private/Files/Config/MountProviderCollection.php",
            "line": 85,
            "function": "getMountsFromProvider",
            "class": "OC\\Files\\Config\\MountProviderCollection",
            "type": "->",
            "args": [
              "*** sensitive parameters replaced ***",
              {
                "__class__": "OC\\User\\User"
              },
              {
                "__class__": "OC\\Files\\Storage\\StorageFactory"
              }
            ]
          },
          {
            "function": "OC\\Files\\Config\\{closure}",
            "class": "OC\\Files\\Config\\MountProviderCollection",
            "type": "->",
            "args": [
              "*** sensitive parameters replaced ***"
            ]
          },
          {
            "file": "/var/www/html/lib/private/Files/Config/MountProviderCollection.php",
            "line": 84,
            "function": "array_map",
            "args": [
              {
                "__class__": "Closure"
              },
              {
                "1": "*** sensitive parameters replaced ***"
              }
            ]
          },
          {
            "file": "/var/www/html/lib/private/Files/Config/MountProviderCollection.php",
            "line": 102,
            "function": "getUserMountsForProviders",
            "class": "OC\\Files\\Config\\MountProviderCollection",
            "type": "->",
            "args": [
              {
                "__class__": "OC\\User\\User"
              },
              {
                "1": "*** sensitive parameters replaced ***"
              }
            ]
          },
          {
            "file": "/var/www/html/lib/private/Files/SetupManager.php",
            "line": 418,
            "function": "getUserMountsForProviderClasses",
            "class": "OC\\Files\\Config\\MountProviderCollection",
            "type": "->",
            "args": [
              {
                "__class__": "OC\\User\\User"
              },
              [
                "OCA\\Files_External\\Config\\ConfigAdapter"
              ]
            ]
          },
          {
            "file": "/var/www/html/lib/private/Files/Mount/Manager.php",
            "line": 75,
            "function": "setupForPath",
            "class": "OC\\Files\\SetupManager",
            "type": "->",
            "args": [
              "/thomas/files/My Uploads"
            ]
          },
          {
            "file": "/var/www/html/lib/private/Files/View.php",
            "line": 1418,
            "function": "find",
            "class": "OC\\Files\\Mount\\Manager",
            "type": "->",
            "args": [
              "/thomas/files/My Uploads"
            ]
          },
          {
            "file": "/var/www/html/apps/dav/lib/Connector/Sabre/Directory.php",
            "line": 183,
            "function": "getFileInfo",
            "class": "OC\\Files\\View",
            "type": "->",
            "args": [
              "/thomas/files/My Uploads"
            ]
          },
          {
            "file": "/var/www/html/3rdparty/sabre/dav/lib/DAV/Tree.php",
            "line": 95,
            "function": "getChild",
            "class": "OCA\\DAV\\Connector\\Sabre\\Directory",
            "type": "->",
            "args": [
              "My Uploads"
            ]
          },
          {
            "file": "/var/www/html/3rdparty/sabre/dav/lib/DAV/Server.php",
            "line": 971,
            "function": "getNodeForPath",
            "class": "Sabre\\DAV\\Tree",
            "type": "->",
            "args": [
              "files/thomas/My Uploads/cloudbeats.cbbackup"
            ]
          },
          {
            "file": "/var/www/html/3rdparty/sabre/dav/lib/DAV/Server.php",
            "line": 1664,
            "function": "getPropertiesIteratorForPath",
            "class": "Sabre\\DAV\\Server",
            "type": "->",
            "args": [
              "files/thomas/My Uploads/cloudbeats.cbbackup",
              [
                "{DAV:}displayname",
                "{http://nextcloud.org/ns}share-download-limits",
                "{DAV:}getlastmodified",
                "{DAV:}getetag",
                "{DAV:}getcontenttype",
                "And 42 more entries, set log level to debug to see all entries"
              ],
              0
            ]
          },
          {
            "file": "/var/www/html/3rdparty/sabre/dav/lib/DAV/Server.php",
            "line": 1649,
            "function": "writeMultiStatus",
            "class": "Sabre\\DAV\\Server",
            "type": "->",
            "args": [
              {
                "__class__": "Sabre\\Xml\\Writer",
                "elementMap": [],
                "contextUri": "/remote.php/dav/",
                "namespaceMap": {
                  "DAV:": "d",
                  "http://sabredav.org/ns": "s",
                  "http://owncloud.org/ns": "oc",
                  "http://nextcloud.org/ns": "nc"
                },
                "classMap": []
              },
              {
                "__class__": "Generator"
              },
              false
            ]
          },
          {
            "file": "/var/www/html/3rdparty/sabre/dav/lib/DAV/CorePlugin.php",
            "line": 346,
            "function": "generateMultiStatus",
            "class": "Sabre\\DAV\\Server",
            "type": "->",
            "args": [
              {
                "__class__": "Generator"
              },
              false
            ]
          },
          {
            "file": "/var/www/html/3rdparty/sabre/event/lib/WildcardEmitterTrait.php",
            "line": 89,
            "function": "httpPropFind",
            "class": "Sabre\\DAV\\CorePlugin",
            "type": "->",
            "args": [
              {
                "__class__": "Sabre\\HTTP\\Request"
              },
              {
                "__class__": "Sabre\\HTTP\\Response"
              }
            ]
          },
          {
            "file": "/var/www/html/3rdparty/sabre/dav/lib/DAV/Server.php",
            "line": 472,
            "function": "emit",
            "class": "Sabre\\DAV\\Server",
            "type": "->",
            "args": [
              "method:PROPFIND",
              [
                {
                  "__class__": "Sabre\\HTTP\\Request"
                },
                {
                  "__class__": "Sabre\\HTTP\\Response"
                }
              ]
            ]
          },
          {
            "file": "/var/www/html/apps/dav/lib/Connector/Sabre/Server.php",
            "line": 49,
            "function": "invokeMethod",
            "class": "Sabre\\DAV\\Server",
            "type": "->",
            "args": [
              {
                "__class__": "Sabre\\HTTP\\Request"
              },
              {
                "__class__": "Sabre\\HTTP\\Response"
              }
            ]
          },
          {
            "file": "/var/www/html/apps/dav/lib/Server.php",
            "line": 398,
            "function": "start",
            "class": "OCA\\DAV\\Connector\\Sabre\\Server",
            "type": "->",
            "args": []
          },
          {
            "file": "/var/www/html/apps/dav/appinfo/v2/remote.php",
            "line": 21,
            "function": "exec",
            "class": "OCA\\DAV\\Server",
            "type": "->",
            "args": []
          },
          {
            "file": "/var/www/html/remote.php",
            "line": 145,
            "args": [
              "/var/www/html/apps/dav/appinfo/v2/remote.php"
            ],
            "function": "require_once"
          }
        ],
        "File": "/var/www/html/apps/files_external/lib/Config/ConfigAdapter.php",
        "Line": 115,
        "Hint": "Storage is temporarily not available"
      }
    },
    "message": "Storage with mount id 27 is not available",
    "exception": {},
    "CustomMessage": "Storage with mount id 27 is not available"
  }
}

I have some folders on the same Hetzner Storagebox as external storage on my Nextcloud via WebDAV. When I mount this storagebox locally via sshfs I can see that the file I uploaded is there with a current timestamp:

root@ubuntu-cx11-02:/var/lib/docker/volumes/nextcloud-docker-compose_nextcloud/_data/data # ll ~/mnt/hetzner/Users/thomas/Uploads/cloudbeats.cbbackup -rt
.rw-r--r-- hetzner hetzner 41 MB 7 minutes ago --  /root/mnt/hetzner/Users/thomas/Uploads/cloudbeats.cbbackup

Some time later my "Uploads" external storage folder is available again: