User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:91.0) Gecko/20100101 Firefox/91.0

Steps to reproduce:

• Create a new mail
• Attach a pdf
• Double click on the pdf to see and check what you are attaching

Actual results:

Attachment do not open and this error is notified:

<FILENAME>.pdf could not be opened, because the associated helper application does not exist. Change the association in your preferences.

Expected results:

The pdf should have been opened by the associated application that I set in the settings (in this case okular)

Can reproduce on Manjaro 21.1.1, fully up to date, with the aforementioned steps.

Thunderbird 91.1.0 is affected.

I have set Foxit Phantom (opening with Wine) as the association, and this worked before the update.

Do you see this when opening the PDF from other parts of Thunderbird, like the inbox. I am just wondering as 91 comes with a built-in PDF viewer if there might be something different in the compose window.

Have you restated the preferred application post V91 install? My understanding was it would revert to the internal viewer. (Not that that means much)

(In reply to Matt from comment #2)

Do you see this when opening the PDF from other parts of Thunderbird, like the inbox. I am just wondering as 91 comes with a built-in PDF viewer if there might be something different in the compose window.

No, it's just on new emails. Once sent, from the sent box, I am able to open and see the attachment.

Have you restated the preferred application post V91 install? My understanding was it would revert to the internal viewer. (Not that that means much)

Can you help me understand how it is possible to "restate" the preferred application? If you mean trying to change the association in the menu then yes, I did it without success.

Thanks!

I can verify the above problem and it is reproducible.
Running Thunderbird 91.1.2 (64-bit) under Windows 10 (64-bit) Build 19043.1237.

The issue has only arisen since Thunderbird was updated recently. Problem identified when:

• composing new email
• forwarding an existing email

A .PDF file is attached to the email in either of the above circumstances. If attempting to Open the PDF, error arises:

C:\Users\xxxxxxx\AppData\Local\Temp\nsmail-2.pdf could not be opened, because the associated helper application does not exist. Change the association in your preferences.

The PDF <will> Open with no problem for an <existing> email. Have tried changing/removing the Content/Type entry in,
TOOLS > PREFERENCES > FILES & ATTACHMENTS
with no affect.

Suggest there is a bug in the above release of Thunderbird.

I have the same issue exactly. I have tried all that is mentioned above with the same results. Another thing to note is that this affects .pdf attachments only. I have tried with other file extensions and they open fine.

Disappointing that this was reported 2 months ago and no fix.

Isn't this a duplicate of bug 1734428?

(In reply to WaltS48 [:walts48] from comment #6)

Isn't this a duplicate of bug 1734428?

NO!! this isn't a duplicate of 1734428, in that case the .pdf was opening in firefox. If you read the bug report is clearly states that .pdf files will NOT open in any application from the compose window.

I think this bug should be a priority as not being able to preview attachments to assure that the correct file is attached makes the program unusable for those of us that attach .pdf files to the majority of our emails.

I prefer to have my .pdf files open in my .pdf reader/editor program but I would be satisfied (in the short term) if they would just open at all.

Yes I think this is a duplicate, or at least will be fixed by bug 1732248#c28

And I have the same problem (pdf attachments do not open for viewing when creating an e-mail message). I tried different builds of the program. Now I am on version 95.0b2, the problem is not fixed.

(In reply to ivan_fabr from comment #9)

And I have the same problem (pdf attachments do not open for viewing when creating an e-mail message). I tried different builds of the program. Now I am on version 95.0b2, the problem is not fixed.

Using 95.0b2 on Fedora 34 Linux, I don't get the error message.

If I select the "Action" to open it in my "Document Viewer (default)" rather than "Preview in Thunderbird", the attachment opens in Firefox.

Understanding that we all work differently, I see a couple workarounds.

1. Open the attachment in your preferred application to verify it is the correct file, before attaching it to the email.
2. Set the Action to "Preview in Thunderbird" while composing, and return it to your preferred setting when reading email.
3. Try testing with a new test profile, or use Help > Troubleshoot Mode to see if an extension is causing the error message.

Problem is not fixed and work arounds are too cumbersome for those of us that use attachments frequently. There are many bug reports filed on this and most have been closed claiming fixed or duplicate but the bug still very much exists.

As I stated, I can't reproduce, and don't get the error.

The bug where users wanted it to open in a tab in the main Thunderbird window using the built-in PDF Viewer from the composition window is fixed. bug 1734428.

Confirming because others are reporting the issue, but likely a dupe of bug 1698140.

(In reply to WaltS48 [:walts48] from comment #12)

As I stated, I can't reproduce, and don't get the error.

The bug where users wanted it to open in a tab in the main Thunderbird window using the built-in PDF Viewer from the composition window is fixed. bug 1734428.

Confirming because others are reporting the issue, but likely a dupe of bug 1698140.

You are running 95.0b2 on Fedora 34 Linux.
I am running 91.3.0 under Windows 10 x64. The problem most definitely persisted for .PDF files, but no other file type.

However, after some trial & error I think I may have somehow "fixed" the problem:
PREFERENCES > FILES & ATTACHMENTS the Action is set to ALWAYS ASK for /all/ Content Types

• WRITE a new email
• Attach a .PDF and a .JPEG
• Double-click .JPEG and an Open prompt appears
• Double-click .PDF and an Open prompt appears! <yay>

The Open prompt for the .PDF does state,
"You have chosen to open xxxxxxxxxxxx.PDF Which is: Firefox HTML document ...." - which does seem peculiar

Hope this helps.

(In reply to WaltS48 [:walts48] from comment #10)

(In reply to ivan_fabr from comment #9)

And I have the same problem (pdf attachments do not open for viewing when creating an e-mail message). I tried different builds of the program. Now I am on version 95.0b2, the problem is not fixed.

Using 95.0b2 on Fedora 34 Linux, I don't get the error message.

If I select the "Action" to open it in my "Document Viewer (default)" rather than "Preview in Thunderbird", the attachment opens in Firefox.

Understanding that we all work differently, I see a couple workarounds.

1. Open the attachment in your preferred application to verify it is the correct file, before attaching it to the email.
2. Set the Action to "Preview in Thunderbird" while composing, and return it to your preferred setting when reading email.
3. Try testing with a new test profile, or use Help > Troubleshoot Mode to see if an extension is causing the error message.

Sorry for my English.

I have 4 computers on Windows 10. The problem arose only on one of them.
Answers according to your list:

1. Yes, this is the correct pdf file
2. On TB 95.0b2 it works, on 91.3.0 it does not work. And this is not a way out of the situation - we send up to 100 letters a day. Switching to the viewing method every time through the settings is unrealistic.
3. If I create a new profile, then there is no problem. But I need the current profile to work.

Maybe the information of the user Popkiss will help you.

(In reply to Popkiss from comment #13)

(In reply to WaltS48 [:walts48] from comment #12)

I am running 91.3.0 under Windows 10 x64. The problem most definitely persisted for .PDF files, but no other file type.

However, after some trial & error I think I may have somehow "fixed" the problem:
PREFERENCES > FILES & ATTACHMENTS the Action is set to ALWAYS ASK for /all/ Content Types

• WRITE a new email
• Attach a .PDF and a .JPEG
• Double-click .JPEG and an Open prompt appears
• Double-click .PDF and an Open prompt appears! <yay>

The Open prompt for the .PDF does state,
"You have chosen to open xxxxxxxxxxxx.PDF Which is: Firefox HTML document ...." - which does seem peculiar

Hope this helps.

As you are using Windows and Firefox - please try the following:
THUNDERBIRD - Preferences > General
Files & Attachments
Content TYpe: Firefox HTML Document change Action from Firefox to Adobe Acrobat
Content Type: PDF set Action as Adobe Acrobat
testing opening of pdf
Then reset - Content TYpe: Firefox HTML Document change Action back to say Action: Firefox default

Please report back on REsults

For those of you using Linux OS who get this message:
<FILENAME>.pdf could not be opened, because the associated helper application does not exist. Change the association in your preferences.

Is Firefox your default browser ? What is default browser?
Preferences > General
Files & Attachments
Content TYpe: HTML Document - What is set up as the Action ?
Content Type : PDF - What is set up as the Action ?

(In reply to Anje from comment #17)

For those of you using Linux OS who get this message:
<FILENAME>.pdf could not be opened, because the associated helper application does not exist. Change the association in your preferences.
Is Firefox your default browser ? What is default browser?
Preferences > General
Files & Attachments
Content TYpe: HTML Document - What is set up as the Action ?
Content Type : PDF - What is set up as the Action ?

Hi, and many thanks for your answer.
Given that, until today, I work around the problem by using "Preview in Thunderbird" action for "Portable Document Format (PDF)" Content type, your message got me curious and so I looked into my settings for "Content Type" -> "HTML Document" and found "Use Firefox Web Browser (default)", so out of curiosity I've changed it to "Always Ask" and the error disappeared, Thunderbird started actually to ask me what to do with the file.
So I tried to set "okular" as default action for "HTML document" and voilà, Thunderbird started opening pdf again.
What is funny is that Thunderbird is totally ignoring the setting for "Portable Document Format (PDF)".

I don't know if what I wrote above helps in some way, but it surely helped me solving my problem.

Thanks!

Raoul

(In reply to rasca from comment #18)

(In reply to Anje from comment #17)

For those of you using Linux OS who get this message:
<FILENAME>.pdf could not be opened, because the associated helper application does not exist. Change the association in your preferences.
Is Firefox your default browser ? What is default browser?
Preferences > General
Files & Attachments
Content TYpe: HTML Document - What is set up as the Action ?
Content Type : PDF - What is set up as the Action ?

Hi, and many thanks for your answer.
Given that, until today, I work around the problem by using "Preview in Thunderbird" action for "Portable Document Format (PDF)" Content type, your message got me curious and so I looked into my settings for "Content Type" -> "HTML Document" and found "Use Firefox Web Browser (default)", so out of curiosity I've changed it to "Always Ask" and the error disappeared, Thunderbird started actually to ask me what to do with the file.
So I tried to set "okular" as default action for "HTML document" and voilà, Thunderbird started opening pdf again.
What is funny is that Thunderbird is totally ignoring the setting for "Portable Document Format (PDF)".

I don't know if what I wrote above helps in some way, but it surely helped me solving my problem.

Thanks!

Raoul

TEST:
You did it correct. At least you know a workaround, but can you now reset as it should be.
Why ? Because I did the same as you and when I reset back to how it should be, the pdf continued to work.
"Portable Document Format (PDF)" set "okular"
"HTML document" set "Use Firefox default"

Please report back with results.

(In reply to Anje from comment #19)

(In reply to rasca from comment #18)

(In reply to Anje from comment #17)

For those of you using Linux OS who get this message:
<FILENAME>.pdf could not be opened, because the associated helper application does not exist. Change the association in your preferences.
Is Firefox your default browser ? What is default browser?
Preferences > General
Files & Attachments
Content TYpe: HTML Document - What is set up as the Action ?
Content Type : PDF - What is set up as the Action ?

Hi, and many thanks for your answer.
Given that, until today, I work around the problem by using "Preview in Thunderbird" action for "Portable Document Format (PDF)" Content type, your message got me curious and so I looked into my settings for "Content Type" -> "HTML Document" and found "Use Firefox Web Browser (default)", so out of curiosity I've changed it to "Always Ask" and the error disappeared, Thunderbird started actually to ask me what to do with the file.
So I tried to set "okular" as default action for "HTML document" and voilà, Thunderbird started opening pdf again.
What is funny is that Thunderbird is totally ignoring the setting for "Portable Document Format (PDF)".

I don't know if what I wrote above helps in some way, but it surely helped me solving my problem.

Thanks!

Raoul

TEST:
You did it correct. At least you know a workaround, but can you now reset as it should be.
Why ? Because I did the same as you and when I reset back to how it should be, the pdf continued to work.
"Portable Document Format (PDF)" set "okular"
"HTML document" set "Use Firefox default"

Please report back with results.

If I do like you said, it opens the PDF via Firefox. Which compared to before is still something, but it doesn't fix the issue.
Problem is that it sees the pdf as an HTML document...

(In reply to rasca from comment #20)

TEST:
You did it correct. At least you know a workaround, but can you now reset as it should be.
Why ? Because I did the same as you and when I reset back to how it should be, the pdf continued to work.
"Portable Document Format (PDF)" set "okular"
"HTML document" set "Use Firefox default"

Please report back with results.

If I do like you said, it opens the PDF via Firefox. Which compared to before is still something, but it doesn't fix the issue.
Problem is that it sees the pdf as an HTML document...

Thanks for feedback.
This implies those who have pdf auto opening in a browser can use the info to reset as in my case.
Those who get the error - associated helper application does not exist - can get a fix by setting the Content Type for HTML to use a pdf program - not ideal, but it works as a workaround.
Not sure whether this is OS specific as I was using Windows 10 and you Linux Ubuntu.

But hopefully the information will help developers to understand the problem so they can get a fix.

(In reply to Anje from comment #21)

(In reply to rasca from comment #20)

TEST:
You did it correct. At least you know a workaround, but can you now reset as it should be.
Why ? Because I did the same as you and when I reset back to how it should be, the pdf continued to work.
"Portable Document Format (PDF)" set "okular"
"HTML document" set "Use Firefox default"

Please report back with results.

If I do like you said, it opens the PDF via Firefox. Which compared to before is still something, but it doesn't fix the issue.
Problem is that it sees the pdf as an HTML document...

Thanks for feedback.
This implies those who have pdf auto opening in a browser can use the info to reset as in my case.
Those who get the error - associated helper application does not exist - can get a fix by setting the Content Type for HTML to use a pdf program - not ideal, but it works as a workaround.
Not sure whether this is OS specific as I was using Windows 10 and you Linux Ubuntu.

But hopefully the information will help developers to understand the problem so they can get a fix.

Let's hope for it. Thanks!