New outlook update (Build 19929.20164) - Bug where I locally can't see the picture in my signature, but other people on previous builds can see it

Dany G 30 Reputation points
2026-05-13T19:42:01.5+00:00

As described in the title, since I updated my outlook today, I can't see the picture in my signature anymore. It shows as a red X.

I've tried resetting my computer, adding a new account, creating a new signature, adding an image via the icon instead of copy/pasting, and nothing seems to work.

I can't see the picture in my signatures, but other users with previous Outlook versions can see them perfectly fine.

This is a bug with the new patch, but is there a work-around established yet?

Thanks,

Outlook | Windows | Classic Outlook for Windows | For business
Answer accepted by question author
Vy Nguyen 11,415 Reputation points Microsoft External Staff Moderator
2026-05-13T21:36:56.7633333+00:00

Hi @Dany G, 

I hope you're doing well today. 

Based on your description, the behavior you are experiencing is consistent with a recently reported issue affecting newer Outlook builds (including Version 2604, Build 19929.20164). In these cases, images embedded in email signatures may appear as a red “X” within the Outlook client, even though they are correctly included in the email. 

Our findings indicate that: 

  • This is a client-side rendering issue introduced in the newer Outlook build. 
  • The signature image itself is not missing or corrupted, as it remains visible to recipients and in other Outlook experiences (such as Outlook on the web or earlier builds). 
  • Similar regressions have been observed in past updates and were typically resolved in subsequent releases.  

At this time, this issue has not yet been formally documented in the official release notes, but it aligns with ongoing reports and known behavior patterns following recent updates. 

While we wait for a permanent fix, you may consider the following options: 

1/ Use a hosted image 

  • To ensure the signature image displays consistently across Outlook versions, host every signature image on a publicly accessible HTTPS location, since linked images can otherwise fail to render and may show as a red X in Outlook under certain conditions. 
  • In addition, avoid Base64-encoded images and avoid cid image references, and instead set an explicit width and height for each image while also matching those dimensions in the image’s inline formatting, because this helps prevent size distortion and reduces the chance that the image is treated as an attachment rather than an inline signature element. 

2/ Allow Outlook to display externally referenced pictures for trusted content 

  • Open Classic Outlook > Options > Trust Center.  
  • Select Automatic Download, and make sure Outlook is not blocking pictures in HTML messages for trusted scenarios.

User's image

  • After saving the change, close Outlook and reopen it, then start a brand-new email to confirm whether the signature image now displays during compose.  

Classic Outlook is designed to block automatic picture downloads by default, and adjusting this setting can restore local rendering when the image is treated as external content. Block or unblock automatic picture downloads in classic Outlook email messages - Microsoft Support 

3/ Recreate the signature so Outlook rebuilds the image reference cleanly 

  • In Classic Outlook, open the Signature settings and create a new signature entry (rather than editing the existing one).  
  • Insert the image using the built-in picture insert option in the signature editor, then save and set the new signature as the default for new messages.  
  • Close the signature window, open a new email, and verify the image appears correctly in the message body before sending.  

Microsoft’s signature workflow stores and formats signature content, including images, in a structured way, and recreating it forces Outlook to regenerate the underlying signature assets using the latest build behavior. How to add and change an email signature in Outlook - Microsoft Support 

4/ Check the Windows setting that can cause HTTPS images to show as a red X 

  • Close Outlook completely.  
  • Open Windows Internet Options, go to Advanced, and under Security ensure the option that prevents saving encrypted pages to disk is turned off.  
  • Restart Outlook and test again by composing a new email and checking whether the signature image renders instead of the red X.  

Microsoft documents that HTTPS linked images can display as a red X when that Windows setting is enabled, and disabling it allows Outlook to cache and display the image properly. HTTPS linked images in HTML emails display the red X - Outlook | Microsoft Learn 

I hope the information I shared earlier was somewhat helpful in addressing your issue. If you have any further questions or updates, please don’t hesitate to share. I’m always happy to assist further if needed.      

Thank you for your patience and your understanding. I look forward to continuing the conversation. 

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have any extra questions about this answer, please click "Comment".             

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread. 

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  1. AI answer

    2026-05-13T19:42:25.72+00:00

    The described behavior matches a known issue where inline images in Outlook signatures are affected by specific Outlook/Exchange builds or updates.

    From the available information, there are two relevant patterns:

    1. Server-side issue (Exchange 2016 + Outlook on the web)
      In Exchange Server 2016 environments, images inserted as data URIs in signatures created via Outlook on the web were not promoted to inline images, causing them to appear as a red X to some recipients. This was fixed by installing a newer cumulative update on the server side (Cumulative Update 11 or later for Exchange Server 2016). If the environment uses Exchange Server 2016 and signatures are managed or generated via Outlook on the web, ensure the Exchange server is updated to at least Cumulative Update 11 or a later cumulative update.
    2. Client-side issues with signatures and images
      Other Outlook builds have had bugs related to signatures and inline images that were later fixed in subsequent builds. In those cases, the effective workarounds were:
      • Updating Outlook to a newer build once Microsoft released a fix.
      • Temporarily removing inline images from signatures, or avoiding signature add-ins that inject images, until the fix was rolled out.
      • In some scenarios, clearing Outlook cache or resetting certain profile/registry data helped when cached data prevented signatures from syncing or displaying correctly.

    Given that:

    • The image appears as a red X only locally in the updated build.
    • Other users on previous builds can see the image correctly.

    This strongly indicates a client-side regression in the new Outlook build. The practical options, based on similar documented issues, are:

    1. Check for and install any newer Outlook build that may already contain a fix for signature/inline-image regressions.
    2. Temporarily remove or simplify the signature (for example, use a text-only signature) until a newer build resolves the issue.
    3. If signatures are generated or synced from the server (Exchange 2016/Outlook on the web), ensure the Exchange server is updated to at least Cumulative Update 11 or later.

    If the environment is managed by an IT department, coordinate with the administrator to:

    • Confirm the Exchange version and cumulative update level.
    • Confirm whether Microsoft has released a newer Outlook build in the chosen update channel that addresses signature image display issues.

    References:

    AI-generated content may be incorrect. Read our transparency notes for more information.

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