I seem to have a problem with uploading some picture and not other's and I can't figure out what the problem is. When I disable the html5 uploader and use the basic one there is an error message that appears. 

I've also tried saving the images as other supported filetypes and resaving as a new jpeg image and the error still occurs.  Most other pictures work fine and I love this plugin.

I have to admit that I never came across this error. So, I'm not sure about the reason for the error at the moment.

It seems the error is connected with exif data contained in images and something going wrong when saving the data. What I find rather strange is the strings showing up in the error message as "Orientation" and "Exif_IFD_Pointer" because Tidypics does only save quite a few exif field values and these are not among them. Image orientation info is only read on image upload (and orientation corrected when needed). But this info is not saved (wouldn't make any sense anyway after already correcting the orientation).

May I ask if you use any other plugin (namely jssor) beside Tidypics? If I remember correctly, the developer of this plugin proposed some modification to save all exif data contained in an image (while I have included some of the changes suggested by the developer this one isn't in Tidypics). In case you have made the changes suggested this might explain the problem. Then some invalid characters within the exif data fields might cause the errors. In this case I can only suggest to revert these changes, i.e. restoring the original Tidypics code as I can't provide any support for these modifications.

I also wonder why the problem persist when changing the image format as exif data would only be within jpg/jpeg images.

If the problem is also happening on an unmodified version of Tidypics without any other plugins adding functionality to Tidypics: could you send me an example image that shows the error on upload for testing? Without being able to reproduce the issue it's quite impossible to come up with a fix if there's indeed anything broken in Tidypics.

I Use several other plugins, but none other to modify photo's or that work with tidypics. I do use your version of IZAP, but again, not for photo upload.  I actually enabled the experimental options:

1. Image size/resolution reduction on client-side before upload (EXPERIMENTAL!)
2. Remove exif data from image files before upload (EXPERIMENTAL)

Now uploading works fine in both basic and html5 uploaders.

I can still provide an image that causes the error if you would like.

Using the option to remove the exif data on client side is kind of a workaround. It's fine if you really don't require any exif data at any time but you won't be able to restore them later if you want to make use of it as they are simple not available.

If you want to provide me an example image I can at least try to investigate what the problem might be. Then it might not be necessary for client-side removal of the data. Just send it to iionly @ gmx . de . I can't promise to really be able to fix the issue at the moment.

@DEYLORD Are there any pending upgrades of Elgg core that you haven't executed yet since upgrading? Is it Elgg 1.9 you started to upgrade from or was it a version older than 1.9? Is there an upgrade button displayed on the Tidypics plugin settings page?

If uploading new images work and they are correctly displayed  but images upgraded before on an older version of Elgg my first idea was that the data directory structure has not yet migrated. But that should only be the case when the older images were uploaded on Elgg 1.8 or older. Nonetheless, if there are any pending upgrades either from Elgg or Tidypics, first run these.

Is the newly uploaded image saved in the data directory at the same location you also see the older image files currently not displayed on the site or is the directory structure where these images are to be found completely different. The latter would most likely mean that you haven't run the data directory migration yet.

Are file permissions AND file owner and group of the older images files the same as for the new image files not only of the data directory itself but also of the subdirectories and files within it? If not, that might be the problem. But I wonder why these should have changed in the first place when you only upgraded to a newer version of Elgg (and upgraded the plugins). Have you done anything else?

In case you did something else than just upgrading your Elgg site - like moving to another server - it might be that setting the timezone in php.ini (or alternatively setting it in Elgg's settings.php or .htaccess) could help. To be honest I don't know if this has been still relevant on Elgg 1.12 as I haven't coded on any Elgg 1.x version for quite some time anymore already. In any case, it won't hurt to set it and it might indeed help if the timezone on the new server difers from the timezone on the previous server.

@iionly Thank you for your answer.
No, there are no pending updates. I want to go to Elgg 2.0.0. and more but for the moment the result is not convincing... for example, I find a empty page. And I would like to solve the Tidypics problem before switching to Elgg 2.0.0. My Elgg 1.9 website came from an older version: Elgg 1.7.5. It was a stable production with a Tydipics 1.9.6. 

No, there is no update button displayed on the settings page. 

I think the structure of the data directory is correct. 

Yes, the newly uploaded image saved in the data directory and in the same place as the older image files. No, I didn't do anything only update the website. 

I haven't changed servers. 

Had everything worked correctly on Elgg 1.9? The biggest changes in Elgg came with the upgrade from 1.8 to 1.9 with changes in the data directory structure, and some other changes Tidypics had to be modified for, too. If everything worked fine on your site with Elgg 1.9 it would indicate that the problem has something to do with upgrading your site from 1.9 up 1.12. Have you upgraded directly from Elgg 1.9 to 1.12 or have to upgraded in step (to 1.10, to 1.11 and only then to 1.12)? On Elgg 1.x it would surely be safest to not omit any minor upgrade step, i.e. not leaving Elgg 1.10 and 1.12 out. Tidypics should not have shown up the "Upgrade" button on its plugin settings page after it has already been upgraded to it's latest version compatible with Elgg 1.9 respectively. But in case you haven't done so I would suggest to disable Tidypics and then totally remove the tidypics plugin folder in the mod directory before copying the latest version for Elgg 1.12 to the mod folder and then re-enable Tidpics. Then  you can be sure that no outdated files remain that might cause problems (the same procedure would also be best for any other plugins and even Elgg itself especially when making a larger upgrade of Elgg).

What about profile images and files uploaded with the bundled Files plugin before the upgrade? Are these displayed correctly and can you download the uploaded files? If not, it would indicate that the problem is not only for Tidypics but with any uploaded files in general. If it's only the Tidypics images that fail to show up it might indeed be a problem with the Tidypics plugin only.

Do you see any errors in the server log (Apache and/or PHP error log)? Maybe the log would tell you what the problem is. For testing you might also want to disable any other 3rd party plugins to see if it makes a difference (unlike though as you say that a newly uploaded image shows up but you never know).

Would you have a backup of your site (database, data directory and install folder) that you could re-install to do the upgrade again? That would be the last option if everything else fails to work. But I suspect that some step during the upgrade was either forgotten or not correctly completed.

Yes, everything worked fine with Elgg 1.9. I had upgraded 1.9 to 1.10, 1.11 and finally to 1.12. But I think the upgrad went wrong because, as you say, I tried to download the newly image uploaded. Indeed it is not empty but not complete to be displayed once downloaded.  And as the old images, they are "corrupted". As you say, I'll upgrade it again with my backups. 

If it still doesn't work I'll look at error_log.... Thank you for your answers and help.

@iionly Indeed the update was bad. Now the Tidypics plugin works perfectly and all images displayed. Many thanks for your work!