Setting your blog to private ("Only people I choose" or "Only blog authors" can view the blog) AND classifying it as Adult Content causes login problems when members attempt to view the blog. To workaround this issue, simply turn off one of these options.

Blogger Play isn't showing any images in Firefox. This affects both play.blogger.com and the iGoogle gadget.

Update, 1/28: This has been fixed.

The "create a link" link for Backlinks is currently missing.

Some templates have slight layout issues when used with right-to-left languages. E.g. some text may overlap with parts of the layout.

AdSense is not currently supported for blogs in Hebrew or Arabic.
Update, 2/25: AdSense widget is now enabled in Hebrew and Arabic.

iPhone Email HTML

Posting images to Mail2Blogger from an iPhone will not work if you include text in the email body below the image. The image will appear as a broken image on the blog.

Some labels are displaying an incorrect number of labeled posts.

Update, 1/15: Label counts will become incorrect if you delete a draft post with labels. Until we have fixed this issue, we recommend that you remove labels from draft posts and save before deleting the posts.

Update, 2/15: This was fixed in the 2/12 release of Blogger.

The preview of your blog on the “Fonts and Colors” page may incorrectly show your posts and sidebar in the same column.

Archives page elements set to “Hierarchy” are not showing posts for any months beyond the first three.

Update, 12/19: This has been fixed.

OpenID and Blogger icons are not appearing correctly for comments on blogs with Classic templates.

Update, 7PM: This has been fixed.

Some comment notification emails are not being sent. We are investigating this issue.

Update, 12/6: This has been fixed.

Clicking on image uploaded through the post editor will show a file download box instead of showing the full-size image in the browser. We are currently working to fix this issue. In the meantime, a workaround is to make two changes to the first URL in the image <a> tag:

Update, 12/4: We pushed a fix for this late last night. Uploaded image click-throughs now work correctly again.

1. Replace "-R" with "-h".
2. Replace the image location folder (preceeding something like "s1600-R") with the folder in the second URL.

Old code:
<a href="http://.../uvkJJAw53aw/s1600-R/PICTURE.JPG">
<img src="http://.../sDRgJ2i-NLo/s320/PICTURE.JPG" /></a>

New Code:
<a href="http://.../sDRgJ2i-NLo/s1600-h/PICTURE.JPG">
<img src="http://.../sDRgJ2i-NLo/s320/PICTURE.JPG"/></a>

OpenID

Blogger has removed the URL field for unauthenticated comments. Instead, we're rolling out support for OpenID, a technology for "signing" your comments with your own URL. OpenID lets you comment with the URL you want, while preventing others from impersonating you. Blog admins can turn on OpenID now on Blogger in Draft. Learn more.

The Blogger widget for the Mac OS X Dashboard is incompatible with version 10.5 (Leopard) of the operating system.

Update, 1/28: It appears to work now.

The “Remember Me” login option will not work correctly in Internet Explorer 6.0. The best workaround is to simply use Firefox. However, if you prefer IE, you can add google.com to the list of allowed sites under Internet Options > Privacy.

Update, 11/15/07: This has been fixed! “Remember Me” now works for Internet Explorer.

Video Upload issues

Blogger is currently experiencing sporadic performance issues with video upload. We're working on improving the quality of service for this feature. In the meantime you may be able to successfully upload your video by waiting a bit and trying to upload again later.

The Search Box page element is currently not returning any search results.

Update, 10/24: This has been fixed.

We are aware and currently working to fix the image uploading issue. This issue predominately causes the following error codes:
bX-6tnmaz
bX-ltlqzv

For updates and discussion of this issue, please visit this Hot Topic thread in the Blogger Help Group.

PicasaStorageSpace

Users who have paid for additional storage space on Picasa Web Albums may not be able to use their additional storage space from within Blogger. As a workaround, try first logging into your Picasa Web Albums account (picasaweb.google.com) and logging out; your additional storage space should then be accessible from within Blogger.

Comment moderation email appears broken and without formatting in many email clients. Until this is fixed, the Approve and Reject URLs should be visible at the very bottom in the literal HTML. You can also moderate comments by going to the Posting > Moderate Comments tab in the Blogger interface.

Update, 9/18: This has been fixed.

Animated image files will not stay animated if the file is hosted by Blogger. This happens because Picasa doesn't support animated images and the Blogger-hosted photos are stored in Picasa Web Albums.

The new “Post Feed Redirect” will occasionally stop redirecting clients when it is set to a FeedBurner feed. The workaround for now is to add an “?alt=atom” parameter to the feed URL in your FeedBurner settings.

Update, 8/24: This has been fixed.

Embedded Google Maps can only be edited in Edit HTML mode. Compose mode will change the embedded code so that the map no longer appears, and this may also cause problems using the posting form.

Update, 9/25: This has been fixed (for a week or so now, actually).

Profile interests, favorites, etc. are not currently displayed as links to browse through other profiles.

Update: this has been fixed.

PicasaBlogThisAlignment

Images uploaded to Blogger via Picasa’s BlogThis! feature are not appearing if the alignment is set to “left” or “right.” The current workaround is to upload images with an alignment of “none.”

Update, 2/8/08: This has been fixed for a while, now. Closing.

JavaScriptInTemplate734670

Some script tags inserted manually into the template code, instead of inserted through a HTML/JavaScript page element, will prevent the Template Page Elements tab from fully loading. For instance, some users report that they are unable to view the "Add Page Element" link. To workaround this issue, please ensure that all JavaScript is inserted via a page element.

IndustryOccNonEnglishProfiles

Industry and occupation do not display in non-English profiles.

DeletedPicasaWebAlbum

If you delete all images uploaded to your blog from your Blogger Picasa Web album and then delete that album, you will be unable to upload new images to your blog.

CommentNotificationChar

Comment notification emails sometimes aren't properly displaying special characters (e.g. apostrophes, accents, etc.) in the subject line of the email.

IE6DraggingPhotoIssue

In Internet Explorer 6.0 and in Compose mode, if you upload an image and then drag it to another location in your post, you might be unable to click through to the full size version of the image once the post is published. To avoid this problem, you can either use a different web browser or switch to Edit HTML mode to move the image code manually.

wwwCustomDomainIssue

If you are using a custom domain, your BlogSpot address will only redirect to that domain if it does not have "www" at the beginning. I.e. both xxxxx.blogspot.com and www.xxxxx.blogspot.com will display the blog correctly, but only the former will appear with your custom domain name.

HyphenInProfileSearch

If a profile item (Interests, Favorites, etc.) includes a hyphen (eg: Blogger-Cat), then the profile search will not display any results. To workaround this issue, simply replace the "-" with a "+" in the address bar of the search results page, and you'll get the proper results.

RectangularPhotoDisplay

Some rectangular images uploaded via the Picture widget in Layouts are being displayed as square, and are thus distorted.

A bug that made it trivially easy to accidentally set your blog's language to Albanian has been fixed. If you notice that your blog's archives and other text appears to be in Albanian (and you don't want it to be), use Settings > Formatting to change your blog's language.

Readers with Internet Explorer will see a white background behind polls added with Blogger in draft's Polls page element.

The Polls page element (on Blogger in draft) does not currently work well with non-Roman Unicode characters. Also, you may be unable to save a poll in some languages because the closing date contains non-Roman characters.

Autosave and image upload do not work with the new Safari 3 beta. We're investigating.

Update, 6/12: All fixed! Autosave and image upload, as well as other features of Blogger’s Compose mode work in the Safari 3 beta.

Update, 6/22: A caveat on this: Safari’s text editor implementation has a habit of creating <div> tags around each paragraph under certain, yet-to-be-determined circumstances. If you notice a lot of extra space between paragraphs after using Safari 3’s editor, choose “Edit HTML” and delete the <div> and </div> tags.

The Blogger Dashboard widget for Mac OS X cannot be used to post to the new version of Blogger.

Update, 6/6: Version 1.0.1 of the widget has been released and works with the new Blogger. Download it.

AdSenseWidgetError

Adding or editing an AdSense page element from your Layouts section may return the error message "An internal error occurred. Please try again." As a workaround to this issue, copy your AdSense code from your AdSense account and insert it into an HTML/JavaScript page element in the layouts section of your blog.

CantSeeAddPageElement

Some users report that they are unable to see the “Add Page Element” links in their Template | Page Elements tab. This occurs when the blog incorrectly tries to display from a URL with “www2” instead of “www.” To work around this problem, simply remove the “2” from the URL.

Update, 5/24: If you are still experiencing this issue but do not have a "2" in your URL, then there may be JavaScript causing the "Add Page Element" links to disappear. Please ensure that you put all JavaScript into JavaScript page elements, instead of directly into your template code.

It is currently not possible to add new Feed page elements to your templates. We are working on the issue.

Update, 5/9: it should now be possible to add new Feed page elements to your templates as expected.

Users posting from the Picasa application are unable to log in.

NonEngLangInPicasaWebAlbums

Users who have their Picasa Web Albums language set to a language other than “English (United States)” will not see their albums of photos uploaded through Blogger.

If your are posting photos through the Picasa application, you may see your photos each appearing in individual albums. We are working to correct this problem. The best work around is to go to the blogger application and post a photo. All following photos should appear in that newly created album, including those you post from the Picasa application.

Update: The problem has been fixed such that all future photo uploads should go to the most recent web album created for that blog. We are still working to correct people who have been affected by this bug.

MultipleCommentsModerated

If a blog has comment moderation enabled and receives multiple comments in the same minute to different posts, some of those comments will not appear in the comment moderation list, though they will be counted on the Dashboard as needing moderation. These comments will also not appear on the blog.

The comments have not been lost, and we will be fixing this in the near term to prevent it from happening again. At that time we will also recover the past missing comments so that they can be
moderated.

Comment feeds are not updating correctly for blogs with many comments. The feeds instead only show the earliest comments. A temporary workaround is to add pagination query parameters to the feeds to get the latest comments.

Update, 3/4: This has been fixed. Comment feeds should now show the recent comments for a blog or post, regardless of how many total comments the blog has.

PicasaBlogThis

The initial release of BlogThis! from Picasa to the new version of Blogger in beta has the following problems that we are working to resolve as quickly as possible:

• If you are signed in as a Blogger user, sign out, and then sign back in with your Google account (to post to the beta), you will receive an error. The work around is to close the window and repost from Picasa (signing in with your Google account).
  
• There is no sign out link if you are logged in as a beta user. The workaround is to exit Picasa.
  
• Posting multiple large images sometimes results in the photos not being uploaded properly. The best workaround for the moment is to use the Blogger edit post form to upload the images.

Word 2007’s new Blogger support does not currently work. We are working closely with the Microsoft Word team to fix this.

Update, 2/1: This has been fixed.

Accessing new Blogger at beta.blogger.com and uploading an image via the posting form will result in error code bX-68tbuv. Until this is fixed, the solution is to go to www.blogger.com and log in there, which will redirect correctly to www2.blogger.com for new Blogger accounts.

Nevertheless, update any old bookmarks that have beta.blogger.com to use www.blogger.com instead.

Update, 1/31: This has been fixed. Regardless, use www.blogger.com and not beta.blogger.com.

ArchiveTemplateNotSupported

The “Archive Template” feature, once available to long-time users of old Blogger, is not supported in new Blogger.