How to recover your files and annotations in Mendeley Desktop – July 2018 

 Update on the resolution of the bug that resulted in files and annotations being deleted from users’ Mendeley libraries in May 2018. 

The recent bug that caused some users’ files and annotations to be marked as deleted has now been resolved and the deleted files and annotations have been restored to users’ accounts. If you have been affected by this bug, you can restore your files and annotations to your Mendeley Desktop by following the steps below:

  1. Upgrade to Mendeley Desktop version 1.19.1 or later, on every machine on which you have Mendeley Desktop installed. If you are on an earlier version (1.19 or earlier), the problem may reoccur. If you are not automatically prompted to upgrade then, from the Help menu select ‘Check for upgrades’ and then ‘Check now’ to upgrade to the latest version.
  2. Ensure ‘Synchronize attached files’ is enabled on all instances of Mendeley Desktop that you use. You can check this by selecting ‘Edit settings’ for All Documents and ensuring the check boxes are ticked.
  3. For most users, when you have upgraded you should sync your Mendeley Desktop and the files and associated annotation will be automatically restored.
  4. For users who are using Mendeley Desktop on more than one machine AND did not sync on one or more machines after 24th May you may need to follow a slightly different process in order to restore your files and associated annotations on your Mendeley Desktop. Before you do this you must perform the following checks:

i) Log into Mendeley Web Library . Check that you can see your restored files and associated annotations here. If you do not, do not proceed. If your files and associated annotations are present in Web Library then you can reset the database on your Mendeley Desktop.

ii) Resetting the database on Mendeley Desktop: If your resorted files and associated annotations are available in Mendeley Web Library, then you can reset the database on Mendeley Desktop. To do this, select ‘Reset Mendeley Desktop’ from the Help menu and follow the instructions.

If your files and annotations are not restored in Web Library (step 4i) then please do not proceed with the database reset but contact support.

We are sorry that many of you had to wait a very long time to find out what had happened to your files, and for the stress that may have caused. For more information on what caused the issue and the steps we have taken to ensure it doesn’t happen again, please see this blog post.

If you are still experiencing issues that are not covered in this post please contact Mendeley Support.

Update on the recent problems users have experienced and how we’re fixing them – July 2018

Update on the recent problems users have experienced and how we’re fixing them – July 2018 

Message from Laura Thomson, Head of Reference Management

We know it’s been a difficult time for a number of users who experienced problems as a result of finding some of their PDFs missing from Mendeley. Many of the team here at Mendeley have been researchers ourselves, so we understand the concern losing PDFs and annotations must have caused. We apologize unreservedly. Below you will find an update of what happened and the steps we’ve taken to restore users’ files.

What happened?

Two incidents happened around the same time that affected users’ files and annotations, which meant that some users could not see or access their files and annotations. Firstly, some files that were added to Mendeley before 2012 were accidentally moved from our live storage system to our archive system.  Secondly, a separate bug caused files and annotations to be flagged as deleted in certain circumstances.

What’s the solution?

Our developers have been working full time on fixing these issues since we identified them, with the aim of being able to restore all users’ data as quickly as possible. It has taken us longer than we would have liked to address all the issues, for which we apologize. The following is a summary of the steps we have taken:

For the archiving problem:

  • We’ve identified and stopped the root cause of the problem, so that older files are no longer moved from live storage to archive storage when they shouldn’t be.
  • For users affected by this problem, we’ve restored all but about 3,500 files, and users should see these the next time they sync. Active users who had one or more unrecoverable files in their library will be contacted individually by us via email.

For the bug:

  • We’ve recovered the files and annotations from our backup systems, and restored them to users’ accounts, along with the relations between them. In most cases, your files and annotations will be restored after a sync. If you are using Mendeley Desktop on more than one machine, then additional steps may be required. Please see this blog post for further instructions.
  • We have fixed the root cause issue causing files and annotations to be deleted, and the fix was included in our 1.19.1 release of Mendeley Desktop.

In both cases, we’ve worked with individual researchers who took the time to give us detailed information on the problems they experienced, and tested solutions for us. We are very grateful to those individuals, and all the other researchers who provided us with feedback and insights to help address these issues.

What are we doing to avoid the situation happening again?

We have put in place several measures to make sure that errors of this kind are prevented from happening in future. These include stricter controls around archiving of data, and additional monitoring and alerting across our products and systems to detect problems earlier.

One thing we’ve learned is that recovery from this situation took us too long. Partly this is to do with having very large volumes of user data to deal with. We are sorry that many of you had to wait a very long time to know what had happened to your files, and for the stress that may have caused. While we’re pleased that we’ve been able to restore most files, we are reviewing back-up procedures with the goal of enabling us to recover data much more quickly than we were able to do this time.

What to do if you are still having problems with missing PDFs:

If you are still experiencing issues that are not covered in this post please contact Mendeley Support. Please check the blog and our social media accounts for any further updates.

Update on the missing PDF issue

Message from Laura Thomson, Head of Reference Management

Update 6 July 2018

Our team continues to work round the clock to fix the issues experienced by affected users however, this is a complex issue and it is taking us a little longer than we anticipated. We expect to have a solution deployed by the end of next week for most users, but it is likely it will take us into the week after (week starting 16 July) to fully implement the fix for all users.

Thank you for bearing with us, we appreciate your patience. We will keep you updated via this channel and our social media accounts. 


We know it’s been a difficult time for some users who experienced problems with missing PDFs and issues related to the recent Mendeley Desktop update. Most of us have been researchers ourselves, so we understand the concern that losing PDFs and annotations has caused. We apologize unreservedly.

As you might expect, we’ve been working round the clock to fix the issues experienced by affected users. Our team has now identified the reasons behind these issues and are working to resolve them.

If you had missing PDFs: most users should see these re-appearing in your library over the next few days. Please sync your library to check if your PDFs are restored. This process may take some time so do not worry if you do not see all your PDFs re-appear straight away. If by the end of next week (week of July 2nd) you still have missing PDFs, please contact Mendeley Support.

We recommend that you update to the latest version of the Mendeley software, which is version 1.19.1. You can start an update manually, go to Help and Check for Updates in the Mendeley Desktop.

If you have missing annotations: we can reassure you that these are not lost. To enable us to restore them for you, please upgrade to Mendeley Desktop 1.19.1 or later. Once you have upgraded, your annotations should be restored by the end of next week (week of July 2nd). If this issue is not resolved by then, please also contact Mendeley Support.

You may see your PDFs restored before your annotations reappear.

Finally, we know that we have more to do. We know that some of you are still experiencing crashes when working with certain PDFs and we will work to fix this in a later release. If you are experiencing other issues, please contact Mendeley Support.

Thank you for bearing with us over the past couple of weeks. We especially thank those researchers and Mendeley Advisors who gave us detailed information on the problems they experienced, which helped us to address them for the whole user community. We really appreciate your constant feedback and insights to help us improve Mendeley and serve you better.

We also appreciate that it’s taken us some time to get this information to you – this was because we wanted to be as certain as we could that the information we were providing was correct, and to do that, our developer team worked in detail with a group of individual researchers to make sure we had fully diagnosed and understood the problems they saw. We will keep providing updates through this channel and our social media accounts.

Support Update: PDFs Missing from Desktop and Web Library 

Message from Laura Thomson, Head of Reference Management

Where did my PDFs go?

As some of you may be aware, we are experiencing issues with missing PDFs on Mendeley Desktop and Mendeley Web Library. We know accessing your PDFs is a crucial part of your research and are sorry for the inconvenience this is causing you.

We are working to resolve this as quickly as possible, so you can get back to your research, but we wanted to let you know what is happening and give you a workaround while we solve this issue.

What‘s going on and how do I fix this?

Some users are finding that all PDFs are missing from their library.

If you find your files missing from Mendeley Desktop and Web Library, the files present on your local machine can be restored by reactivating the sync. Click here for the latest information on how to do that. This will also restore the notes and annotations.

This solution may not work for all users. If it has not worked for you, please check if:

You see an error message that the PDF will not open. If so, then click here for more details.

Your PDFs are not syncing to the cloud. If this is the case, then click here for more details.

If the issue you are experiencing is not covered by the above, please contact Support so that we can help you resolve it.

When will this be fixed?

At this time we do not have an exact time when this will be permanently fixed. Please check this blog post, and our social media accounts for the latest updates.

Mendeley Twitter
Mendeley Support Twitter
Mendeley Facebook