Public bug reported:

### 1. Affected Package revision / version

Ubuntu MATE 24.04 (tested using `ubuntu-mate-24.04-desktop-amd64.iso` to
ubuntu-mate-24.04.5-desktop-amd64.iso (the current release at this
writing) tested)

---

### Environment

* **Desktop Environment:** MATE 1.26
* **File Manager:** Caja
* **Text Editor:** Pluma
* **MIME Library:** GLib / GIO / shared-mime-info

---

### 2. Steps to Reproduce

1. Create a 0-byte file (e.g., via `touch "new file"` or by right-clicking on 
the desktop → **Create Document** → **Empty File**).
2. Attempt to open or double-click the file in Caja.

---

### 3. Current Behavior

Triggering the file opens an error dialog:

> *"There is no application installed for Empty document files. Do you
want to search for an application to open this file?"*

Clicking "Yes" does nothing because packagekit/sessioninstaller
integration is unhandled or missing by default, leaving the user unable
to open empty text files natively in Pluma.

---

### 4. Expected Behavior *(optional)*

Zero-byte text files should open directly in Pluma (the default text
editor), consistent with how `text/plain` files behave.

---

### 5. Workaround *(optional)*

* **System-Level Workaround (First Session Script):**
Deploy a script on new user creation / first login session that runs:
```bash
xdg-mime default pluma.desktop application/x-zerosize

```

This automatically creates or updates `$HOME/.config/mimeapps.list` with:
```ini
[Default Applications]
application/x-zerosize=pluma.desktop

```

* **User-Level Terminal Workaround:**
Run the command directly in the terminal:
```bash
xdg-mime default pluma.desktop application/x-zerosize

```

* **User-Level GUI Workaround:**
1. Right-click any 0-byte file in Caja and select **Open With Other 
Application...**.
2. Select **Pluma Text Editor**.
3. Ensure **"Remember this application for 'Empty document' files"** is checked.
4. Click **Open**.

* **Template-Based Workaround (Bypassing Desktop 0-Byte Creation):**
Right-clicking on the desktop → **Create Document** → **Empty File** generates 
a 0-byte file named `"new file"` by default, immediately triggering this issue. 
You can avoid the 0-byte threshold for desktop-created files by populating a 
custom template:
```bash
mkdir -p ~/Templates && echo "" > ~/Templates/"Text Document.txt"

```

This creates a 1-byte file containing a single blank line. Having this
template makes "Text Document" appear as an option when you right-click
in Caja and select **Create Document**, bypassing 0-byte detection
entirely for files created through that menu. *(Note: Standard 0-byte
files created via `touch` or other means will still require the MIME fix
above).*

---

### 6. Suggestions, Investigation and Possible Causes *(optional)*

* **Root Cause:** In both Ubuntu MATE 22.04 and Ubuntu MATE 24.04, 
`/usr/share/applications/mate-mimeapps.list` correctly contains 
`text/plain=pluma.desktop;`. However, GLib's fast-content-type detection 
changed between versions.
* **Comparison:**
* **Ubuntu MATE 22.04:**
```bash
$ touch "new file"
$ gio info "new file" | grep 'standard::fast-content-type'
standard::fast-content-type: text/plain

```

* **Ubuntu MATE 24.04:**
```bash
$ touch "new file"
$ gio info "new file" | grep 'standard::fast-content-type'
standard::fast-content-type: application/x-zerosize

```

Because `application/x-zerosize` lacks a default mapping out-of-the-box
in Ubuntu MATE 24.04, Caja fails to resolve a handler. The fix is very
straightforward to apply.

---

### 7. Other Tests *(optional)*

Tested using `ubuntu-mate-24.04-desktop-amd64.iso`, confirming the
regression is present here while it did not occur in Ubuntu MATE 22.04.
Note that right-clicking on the desktop → **Create Document** → **Empty
File** generates a 0-byte file named `"new file"` by default,
immediately triggering this issue unless a non-empty template file is
used.

---

ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: caja 1.26.3-1build3
ProcVersionSignature: Ubuntu 7.0.0-31.31~24.04.1-generic 7.0.14
Uname: Linux 7.0.0-31-generic x86_64
NonfreeKernelModules: zfs
ApportVersion: 2.28.3-0ubuntu0.1
Architecture: amd64
CasperMD5CheckResult: pass
CasperVersion: 1.498
CloudArchitecture: x86_64
CloudID: nocloud
CloudName: unknown
CloudPlatform: nocloud
CloudSubPlatform: seed-dir (/var/lib/cloud/seed/nocloud)
CurrentDesktop: MATE
Date: Tue Oct 27 06:44:01 2026
LiveMediaBuild: Ubuntu-MATE 24.04.5 LTS "Noble Numbat" - Release amd64 
(20260909)
ProcEnviron:
 LANG=C.UTF-8
 PATH=(custom, no user)
 SHELL=/bin/bash
 TERM=xterm-256color
 XDG_RUNTIME_DIR=<set>
SourcePackage: caja
UpgradeStatus: No upgrade log present (probably fresh install)

** Affects: caja (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug noble

** Description changed:

- Here is the corrected and finalized bug report specifically tailored for
- **Ubuntu MATE 24.04** (with proper quoting for the `gio info` command to
- avoid bash parsing errors):
- 
- ---
- 
- ## Bug Report Template
- 
- > **If you have a question or are not sure about what you are about to post, 
please use the forums instead.**
- > **Also, check for possible duplicate reports here or in the forum before 
submitting this issue.**
- 
- ---
- 
- ### Title
- 
- **Opening 0-byte text files triggers "No application installed" error
- due to `application/x-zerosize` MIME regression**
- 
- ---
- 
  ### 1. Affected Package revision / version
  
  Ubuntu MATE 24.04 (tested using `ubuntu-mate-24.04-desktop-amd64.iso`)
  
  ---
  
  ### Environment
  
  * **Desktop Environment:** MATE 1.26 / 1.28
  * **File Manager:** Caja
  * **Text Editor:** Pluma
  * **MIME Library:** GLib / GIO / shared-mime-info
  
  ---
  
  ### 2. Steps to Reproduce
  
  1. Create a 0-byte file (e.g., via `touch "new file"` or by right-clicking on 
the desktop → **Create Document** → **Empty File**).
  2. Attempt to open or double-click the file in Caja.
  
  ---
  
  ### 3. Current Behavior
  
  Triggering the file opens an error dialog:
  
  > *"There is no application installed for Empty document files. Do you
  want to search for an application to open this file?"*
  
  Clicking "Yes" does nothing because packagekit/sessioninstaller
  integration is unhandled or missing by default, leaving the user unable
  to open empty text files natively in Pluma.
  
  ---
  
  ### 4. Expected Behavior *(optional)*
  
  Zero-byte text files should open directly in Pluma (the default text
  editor), consistent with how `text/plain` files behave.
  
  ---
  
  ### 5. Workaround *(optional)*
  
  * **System-Level Workaround (First Session Script):**
  Deploy a script on new user creation / first login session that runs:
  ```bash
  xdg-mime default pluma.desktop application/x-zerosize
  
  ```
  
- 
  This automatically creates or updates `$HOME/.config/mimeapps.list` with:
  ```ini
  [Default Applications]
  application/x-zerosize=pluma.desktop
  
  ```
- 
  
  * **User-Level Terminal Workaround:**
  Run the command directly in the terminal:
  ```bash
  xdg-mime default pluma.desktop application/x-zerosize
  
  ```
  
- 
  * **User-Level GUI Workaround:**
  1. Right-click any 0-byte file in Caja and select **Open With Other 
Application...**.
  2. Select **Pluma Text Editor**.
  3. Ensure **"Remember this application for 'Empty document' files"** is 
checked.
  4. Click **Open**.
- 
  
  * **Template-Based Workaround (Bypassing Desktop 0-Byte Creation):**
  Right-clicking on the desktop → **Create Document** → **Empty File** 
generates a 0-byte file named `"new file"` by default, immediately triggering 
this issue. You can avoid the 0-byte threshold for desktop-created files by 
populating a custom template:
  ```bash
  mkdir -p ~/Templates && echo "" > ~/Templates/"Text Document.txt"
  
  ```
  
- 
- This creates a 1-byte file containing a single blank line. Having this 
template makes "Text Document" appear as an option when you right-click in Caja 
and select **Create Document**, bypassing 0-byte detection entirely for files 
created through that menu. *(Note: Standard 0-byte files created via `touch` or 
other means will still require the MIME fix above).*
+ This creates a 1-byte file containing a single blank line. Having this
+ template makes "Text Document" appear as an option when you right-click
+ in Caja and select **Create Document**, bypassing 0-byte detection
+ entirely for files created through that menu. *(Note: Standard 0-byte
+ files created via `touch` or other means will still require the MIME fix
+ above).*
  
  ---
  
  ### 6. Suggestions, Investigation and Possible Causes *(optional)*
  
  * **Root Cause:** In both Ubuntu MATE 22.04 and Ubuntu MATE 24.04, 
`/usr/share/applications/mate-mimeapps.list` correctly contains 
`text/plain=pluma.desktop;`. However, GLib's fast-content-type detection 
changed between versions.
  * **Comparison:**
  * **Ubuntu MATE 22.04:**
  ```bash
  $ touch "new file"
  $ gio info "new file" | grep 'standard::fast-content-type'
  standard::fast-content-type: text/plain
  
  ```
  
- 
  * **Ubuntu MATE 24.04:**
  ```bash
  $ touch "new file"
  $ gio info "new file" | grep 'standard::fast-content-type'
  standard::fast-content-type: application/x-zerosize
  
  ```
  
- 
- 
- Because `application/x-zerosize` lacks a default mapping out-of-the-box in 
Ubuntu MATE 24.04, Caja fails to resolve a handler. The fix is very 
straightforward to apply.
+ Because `application/x-zerosize` lacks a default mapping out-of-the-box
+ in Ubuntu MATE 24.04, Caja fails to resolve a handler. The fix is very
+ straightforward to apply.
  
  ---
  
  ### 7. Other Tests *(optional)*
  
  Tested using `ubuntu-mate-24.04-desktop-amd64.iso`, confirming the
  regression is present here while it did not occur in Ubuntu MATE 22.04.
  Note that right-clicking on the desktop → **Create Document** → **Empty
  File** generates a 0-byte file named `"new file"` by default,
  immediately triggering this issue unless a non-empty template file is
  used.
  
  ---
  
  ProblemType: Bug
  DistroRelease: Ubuntu 24.04
  Package: caja 1.26.3-1build3
  ProcVersionSignature: Ubuntu 7.0.0-31.31~24.04.1-generic 7.0.14
  Uname: Linux 7.0.0-31-generic x86_64
  NonfreeKernelModules: zfs
  ApportVersion: 2.28.3-0ubuntu0.1
  Architecture: amd64
  CasperMD5CheckResult: pass
  CasperVersion: 1.498
  CloudArchitecture: x86_64
  CloudID: nocloud
  CloudName: unknown
  CloudPlatform: nocloud
  CloudSubPlatform: seed-dir (/var/lib/cloud/seed/nocloud)
  CurrentDesktop: MATE
  Date: Tue Oct 27 06:44:01 2026
  LiveMediaBuild: Ubuntu-MATE 24.04.5 LTS "Noble Numbat" - Release amd64 
(20260909)
  ProcEnviron:
-  LANG=C.UTF-8
-  PATH=(custom, no user)
-  SHELL=/bin/bash
-  TERM=xterm-256color
-  XDG_RUNTIME_DIR=<set>
+  LANG=C.UTF-8
+  PATH=(custom, no user)
+  SHELL=/bin/bash
+  TERM=xterm-256color
+  XDG_RUNTIME_DIR=<set>
  SourcePackage: caja
  UpgradeStatus: No upgrade log present (probably fresh install)

** Description changed:

  ### 1. Affected Package revision / version
  
  Ubuntu MATE 24.04 (tested using `ubuntu-mate-24.04-desktop-amd64.iso`)
  
  ---
  
  ### Environment
  
- * **Desktop Environment:** MATE 1.26 / 1.28
+ * **Desktop Environment:** MATE 1.26
  * **File Manager:** Caja
  * **Text Editor:** Pluma
  * **MIME Library:** GLib / GIO / shared-mime-info
  
  ---
  
  ### 2. Steps to Reproduce
  
  1. Create a 0-byte file (e.g., via `touch "new file"` or by right-clicking on 
the desktop → **Create Document** → **Empty File**).
  2. Attempt to open or double-click the file in Caja.
  
  ---
  
  ### 3. Current Behavior
  
  Triggering the file opens an error dialog:
  
  > *"There is no application installed for Empty document files. Do you
  want to search for an application to open this file?"*
  
  Clicking "Yes" does nothing because packagekit/sessioninstaller
  integration is unhandled or missing by default, leaving the user unable
  to open empty text files natively in Pluma.
  
  ---
  
  ### 4. Expected Behavior *(optional)*
  
  Zero-byte text files should open directly in Pluma (the default text
  editor), consistent with how `text/plain` files behave.
  
  ---
  
  ### 5. Workaround *(optional)*
  
  * **System-Level Workaround (First Session Script):**
  Deploy a script on new user creation / first login session that runs:
  ```bash
  xdg-mime default pluma.desktop application/x-zerosize
  
  ```
  
  This automatically creates or updates `$HOME/.config/mimeapps.list` with:
  ```ini
  [Default Applications]
  application/x-zerosize=pluma.desktop
  
  ```
  
  * **User-Level Terminal Workaround:**
  Run the command directly in the terminal:
  ```bash
  xdg-mime default pluma.desktop application/x-zerosize
  
  ```
  
  * **User-Level GUI Workaround:**
  1. Right-click any 0-byte file in Caja and select **Open With Other 
Application...**.
  2. Select **Pluma Text Editor**.
  3. Ensure **"Remember this application for 'Empty document' files"** is 
checked.
  4. Click **Open**.
  
  * **Template-Based Workaround (Bypassing Desktop 0-Byte Creation):**
  Right-clicking on the desktop → **Create Document** → **Empty File** 
generates a 0-byte file named `"new file"` by default, immediately triggering 
this issue. You can avoid the 0-byte threshold for desktop-created files by 
populating a custom template:
  ```bash
  mkdir -p ~/Templates && echo "" > ~/Templates/"Text Document.txt"
  
  ```
  
  This creates a 1-byte file containing a single blank line. Having this
  template makes "Text Document" appear as an option when you right-click
  in Caja and select **Create Document**, bypassing 0-byte detection
  entirely for files created through that menu. *(Note: Standard 0-byte
  files created via `touch` or other means will still require the MIME fix
  above).*
  
  ---
  
  ### 6. Suggestions, Investigation and Possible Causes *(optional)*
  
  * **Root Cause:** In both Ubuntu MATE 22.04 and Ubuntu MATE 24.04, 
`/usr/share/applications/mate-mimeapps.list` correctly contains 
`text/plain=pluma.desktop;`. However, GLib's fast-content-type detection 
changed between versions.
  * **Comparison:**
  * **Ubuntu MATE 22.04:**
  ```bash
  $ touch "new file"
  $ gio info "new file" | grep 'standard::fast-content-type'
  standard::fast-content-type: text/plain
  
  ```
  
  * **Ubuntu MATE 24.04:**
  ```bash
  $ touch "new file"
  $ gio info "new file" | grep 'standard::fast-content-type'
  standard::fast-content-type: application/x-zerosize
  
  ```
  
  Because `application/x-zerosize` lacks a default mapping out-of-the-box
  in Ubuntu MATE 24.04, Caja fails to resolve a handler. The fix is very
  straightforward to apply.
  
  ---
  
  ### 7. Other Tests *(optional)*
  
  Tested using `ubuntu-mate-24.04-desktop-amd64.iso`, confirming the
  regression is present here while it did not occur in Ubuntu MATE 22.04.
  Note that right-clicking on the desktop → **Create Document** → **Empty
  File** generates a 0-byte file named `"new file"` by default,
  immediately triggering this issue unless a non-empty template file is
  used.
  
  ---
  
  ProblemType: Bug
  DistroRelease: Ubuntu 24.04
  Package: caja 1.26.3-1build3
  ProcVersionSignature: Ubuntu 7.0.0-31.31~24.04.1-generic 7.0.14
  Uname: Linux 7.0.0-31-generic x86_64
  NonfreeKernelModules: zfs
  ApportVersion: 2.28.3-0ubuntu0.1
  Architecture: amd64
  CasperMD5CheckResult: pass
  CasperVersion: 1.498
  CloudArchitecture: x86_64
  CloudID: nocloud
  CloudName: unknown
  CloudPlatform: nocloud
  CloudSubPlatform: seed-dir (/var/lib/cloud/seed/nocloud)
  CurrentDesktop: MATE
  Date: Tue Oct 27 06:44:01 2026
  LiveMediaBuild: Ubuntu-MATE 24.04.5 LTS "Noble Numbat" - Release amd64 
(20260909)
  ProcEnviron:
   LANG=C.UTF-8
   PATH=(custom, no user)
   SHELL=/bin/bash
   TERM=xterm-256color
   XDG_RUNTIME_DIR=<set>
  SourcePackage: caja
  UpgradeStatus: No upgrade log present (probably fresh install)

** Description changed:

  ### 1. Affected Package revision / version
  
- Ubuntu MATE 24.04 (tested using `ubuntu-mate-24.04-desktop-amd64.iso`)
+ Ubuntu MATE 24.04 (tested using `ubuntu-mate-24.04-desktop-amd64.iso` to
+ ubuntu-mate-24.04.5-desktop-amd64.iso (the current release at this
+ writing) tested)
  
  ---
  
  ### Environment
  
  * **Desktop Environment:** MATE 1.26
  * **File Manager:** Caja
  * **Text Editor:** Pluma
  * **MIME Library:** GLib / GIO / shared-mime-info
  
  ---
  
  ### 2. Steps to Reproduce
  
  1. Create a 0-byte file (e.g., via `touch "new file"` or by right-clicking on 
the desktop → **Create Document** → **Empty File**).
  2. Attempt to open or double-click the file in Caja.
  
  ---
  
  ### 3. Current Behavior
  
  Triggering the file opens an error dialog:
  
  > *"There is no application installed for Empty document files. Do you
  want to search for an application to open this file?"*
  
  Clicking "Yes" does nothing because packagekit/sessioninstaller
  integration is unhandled or missing by default, leaving the user unable
  to open empty text files natively in Pluma.
  
  ---
  
  ### 4. Expected Behavior *(optional)*
  
  Zero-byte text files should open directly in Pluma (the default text
  editor), consistent with how `text/plain` files behave.
  
  ---
  
  ### 5. Workaround *(optional)*
  
  * **System-Level Workaround (First Session Script):**
  Deploy a script on new user creation / first login session that runs:
  ```bash
  xdg-mime default pluma.desktop application/x-zerosize
  
  ```
  
  This automatically creates or updates `$HOME/.config/mimeapps.list` with:
  ```ini
  [Default Applications]
  application/x-zerosize=pluma.desktop
  
  ```
  
  * **User-Level Terminal Workaround:**
  Run the command directly in the terminal:
  ```bash
  xdg-mime default pluma.desktop application/x-zerosize
  
  ```
  
  * **User-Level GUI Workaround:**
  1. Right-click any 0-byte file in Caja and select **Open With Other 
Application...**.
  2. Select **Pluma Text Editor**.
  3. Ensure **"Remember this application for 'Empty document' files"** is 
checked.
  4. Click **Open**.
  
  * **Template-Based Workaround (Bypassing Desktop 0-Byte Creation):**
  Right-clicking on the desktop → **Create Document** → **Empty File** 
generates a 0-byte file named `"new file"` by default, immediately triggering 
this issue. You can avoid the 0-byte threshold for desktop-created files by 
populating a custom template:
  ```bash
  mkdir -p ~/Templates && echo "" > ~/Templates/"Text Document.txt"
  
  ```
  
  This creates a 1-byte file containing a single blank line. Having this
  template makes "Text Document" appear as an option when you right-click
  in Caja and select **Create Document**, bypassing 0-byte detection
  entirely for files created through that menu. *(Note: Standard 0-byte
  files created via `touch` or other means will still require the MIME fix
  above).*
  
  ---
  
  ### 6. Suggestions, Investigation and Possible Causes *(optional)*
  
  * **Root Cause:** In both Ubuntu MATE 22.04 and Ubuntu MATE 24.04, 
`/usr/share/applications/mate-mimeapps.list` correctly contains 
`text/plain=pluma.desktop;`. However, GLib's fast-content-type detection 
changed between versions.
  * **Comparison:**
  * **Ubuntu MATE 22.04:**
  ```bash
  $ touch "new file"
  $ gio info "new file" | grep 'standard::fast-content-type'
  standard::fast-content-type: text/plain
  
  ```
  
  * **Ubuntu MATE 24.04:**
  ```bash
  $ touch "new file"
  $ gio info "new file" | grep 'standard::fast-content-type'
  standard::fast-content-type: application/x-zerosize
  
  ```
  
  Because `application/x-zerosize` lacks a default mapping out-of-the-box
  in Ubuntu MATE 24.04, Caja fails to resolve a handler. The fix is very
  straightforward to apply.
  
  ---
  
  ### 7. Other Tests *(optional)*
  
  Tested using `ubuntu-mate-24.04-desktop-amd64.iso`, confirming the
  regression is present here while it did not occur in Ubuntu MATE 22.04.
  Note that right-clicking on the desktop → **Create Document** → **Empty
  File** generates a 0-byte file named `"new file"` by default,
  immediately triggering this issue unless a non-empty template file is
  used.
  
  ---
  
  ProblemType: Bug
  DistroRelease: Ubuntu 24.04
  Package: caja 1.26.3-1build3
  ProcVersionSignature: Ubuntu 7.0.0-31.31~24.04.1-generic 7.0.14
  Uname: Linux 7.0.0-31-generic x86_64
  NonfreeKernelModules: zfs
  ApportVersion: 2.28.3-0ubuntu0.1
  Architecture: amd64
  CasperMD5CheckResult: pass
  CasperVersion: 1.498
  CloudArchitecture: x86_64
  CloudID: nocloud
  CloudName: unknown
  CloudPlatform: nocloud
  CloudSubPlatform: seed-dir (/var/lib/cloud/seed/nocloud)
  CurrentDesktop: MATE
  Date: Tue Oct 27 06:44:01 2026
  LiveMediaBuild: Ubuntu-MATE 24.04.5 LTS "Noble Numbat" - Release amd64 
(20260909)
  ProcEnviron:
   LANG=C.UTF-8
   PATH=(custom, no user)
   SHELL=/bin/bash
   TERM=xterm-256color
   XDG_RUNTIME_DIR=<set>
  SourcePackage: caja
  UpgradeStatus: No upgrade log present (probably fresh install)

-- 
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Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/2172282

Title:
  Opening 0-byte text files triggers "No application installed" error
  due to application/x-zerosize MIME regression

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