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TOPIC: Revit

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Revit Error: Too Many Elements Missing

Model corruption in Revit can happen. We noticed a common trend about what causes these issues and have compiled possible solutions to implement into your project or firm’s workflow, to reduce the risk of corruption and down-time. In another article we’ve discussed, What Causes Revit Data Corruption? In this article, we will focus on one of the worst instances of model corruption.

“The model {filename}.rvt is missing many elements, and cannot be opened.”

This error indicates corruption in Arch, Struct, or MEP Revit families, where the application does not allow anyone to open the project file. This can affect both projects using or not using Worksets and Worksharing. This message appears when there are more missing elements than Revit will ignore. If there are just a few missing elements, Revit ignores them and attempts to continue opening the model. If there are too many missing elements, the file is unrecoverable and the team will have to restore a previous version of the file or a local file.

There are instances where the Microsol Resources support team can open a case with Autodesk and have the file repaired. Sadly, this does not happen often.

However, sometimes the error only occurs when the ‘audit’ option is checked when opening the file. We will proceed with the understanding that we are able to open the model and that the error appears when ‘Audit’ is checked.

The following are two images of the error message we’ve seen.

Old Message


Revit Error & Possible Causes

Elements in your project are corrupt, causing Revit to report the missing elements.  Here is our tutorial on troubleshooting.

  1. Collect backup files for your local and detached central.
  2. Identify the elements. In the Revit Journal for this session, it is common that the families causing the issue can be identified.
  3. The element corruption may exist in a linked RVT.
    If the linked file has many missing elements and the link cannot be loaded, Revit may present the missing elements warning.
  4. One user is running a different build of Revit.
    They have not installed the same updates that the rest of the team is using.
  5. Packet Loss
    A communication interruption between the local file and the central file. Most likely due to poor internet or network connection.
  6. Too many warnings
    Try to minimize warnings to the best of your ability, especially the following warnings:

    • Any error that indicates a problem that will affect area or volume calculation. Volume requires much more calculation than area.
    • Highlighted walls are attached to, but miss, the highlighted targets
    • Highlighted elements are joined but do not intersect
    • Area or Room separation line is slightly off-axis and may cause inaccuracies
    • Highlighted lines overlap. Lines may not form closed loops and it’s variations
    • Stair errors.
    • Duplicate and Overlapping Elements.
  7. Upgrading an old model/family
    Up until Revit 2016, there were certain elements that ended up getting their IDs changed in 2017. Things like fonts and stairs/railings, in particular, got changed and caused a lot of issues.
Possible Solutions
  1. Open the model without Audit Check
  2. Identify the missing elements
  3. Replace the missing elements from a backup or stable file.
  4. Export Families using Save as / Save as Family / Save as Library
  5. Import families that illustrate errors during the Save as Library process.
  6. Find a user with a working local copy, or the most recent backup without the error, and move forward with the recovered model.

The premise is that this error is caused by one or more corrupt family components. So the solution is to extract all families from an un-corrupted archive of the model (un-corrupted here means that one is able to open the model with an ‘Audit’ check) and load those families into the corrupted version of the model. This overwrites all family definitions including corrupted versions and thus rids the project of the error. Family extraction from a project can be automated by going to Save As > Library > Family.  We need to find a stable family or repair the issues identified in this warning.

The image below was captured during this process, a warning pops up indicating the family is problematic in some way. I moved the warning error box to the lower left of the Revit interface, in order to see and capture the warning next to the status bar. This information and the right Revit journal file can help identify potential problems in the family being exported.

The warning dialog has an option to export the warning, the element ID, and the addressable issue.

However, the challenge with this approach is that large projects contain hundreds of families, and loading them manually becomes tedious. We can automate the process either by using a macro or a dynamo script. Reach out if this is something your team needs.

Once the corrupt family has been identified, one can re-open the model and locate the family in the Project Browser and delete the family (via right-click), or replace the family with an un-corrupted version from the library or archive.

The project should open without error after this (when ‘Audit’ is checked). If there is more than one corrupt family, this process will have to repeat as many times as needed since each run of the Family Size Reporter will crash when processing the first available corrupt family.

Missing Elements Hosted on BIM 360

If the missing elements message is received for a Cloud Workshared model hosted on BIM 360, then the process would be the same (restore a previous version of the model and replace any family corruption). However, the corruption could be isolated to the locally cached copy of a model or link, particularly if the issue is limited to just one user. In this circumstance, the solution is far simpler:

To clear a corrupt/damaged cloud workshared model or outdated link from the system:

    1. Create a folder called Cache on the Desktop.
    2. Move the PacCache and CollaborationCache folders to the folder created on the desktop.
      • Collaboration cache folder location C:\Users\%USERNAME%\AppData\Local\Autodesk\Revit\Autodesk Revit ####\CollaborationCache
      • PacCache folder location C:\Users\%USERNAME%\AppData\Local\Autodesk\Revit\PacCache
    3. Open the problematic file in Revit.
      • Note: This will recreate the cache and clear any corrupt/damaged cloud workshared cache data.
    4. Open the Desktop folders from Step 2 and the original folder location of the Cache files.
    5. Move the files that were not recreated back into the original Cache folders.​​​​​​
      • Note: If none of the files are moved back into the original cache folders, the cache for other projects will need to be recreated which will slow down the initial time it takes to open the file.

An alternate approach, if you have access to a second system:

  1. On the second system, open Revit.
  2. Sign in to your own A360 account.
  3. Open the problematic model.
  4. Copy the newly created CollaborationCache files from the second system to the original system (overwriting).

If the method above does not work, then the more complete Alternate Sledgehammer Approach may help.

  1. With Revit closed, rename the CollaborationCache folder.
    • Note: This will force all model data to be re-cached. If the model can open, then it confirms that the locally cached copy was corrupt. If the issue persists, then the cloud model has become corrupt and will need to be rolled back to a previous version.
Preventative Care

For all Revit projects, Microsol Resources and Autodesk, inc recommended regularly open and audit your Revit model (daily, or weekly) to ensure that any damage or corruption is addressed as soon as possible. It is also important to address warnings to reduce the overall risk of model corruption. Please see our other blog, Revit Project Maintenance Guidelines. Consider taking a class with us, perhaps Revit Family Creation, Online

Extra Help from Microsol Resources

If you are still having persistent issues, you can create a support case and our Technical Team will try and assist you.



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Revit Project Maintenance Guidelines

The first step of any Revit Model Maintenance process is Detach from Central with Audit. However, there is more to cleaning a project than this. This article is a cumulation of thousands of tech support cases, solved and logged in our CRM system.

When a model is not maintained, it takes more system resources, performance is reduced, packets of information lost and corruption in the data is the result. I’ve organized them in the best order possible, but it takes a team to get it all done, while in production.

Here are our recommended procedures for a terrestrial and cloud project.

  1. Sync with Central
  2. Close all local and central files
  3. Detach from Central
  4. Check the Revit Journal
  5. Purge Unused
  6. Export Families to review and audit
  7. Check Worksets
  8. Review and address Warnings
  9. Delete Backup and Temp Folders
  10. Create a new Central Model
  11. Create new Local files


  1. Have all users Sync with Central, SWC, and relinquish all borrowed or owned worksets.
    • Tip: I believe no one should own a workset, only borrow from them.
  2. Close all Local Files. In the BIM 360 world, we have no local files, other than the local cache in APPDATA
  3. The BIM Manager will open the Central model, by selecting “Detach from Central” along with “Audit”. In BIM 360 we can select the project we want to open on the Revit Home page. choose “Open and Audit” at the ellipsis, ” . . . “.
    • When the BIM manager works in the Central Model. No one should attempt to open or create a new local.
    • All work is stopped at this point.
  4. Check the Revit Journal.
    • Journal review can help determine corruption, We can use the Journal to check the Revit build version, locate errors, and even identify bad work habits.
    • I will create a separate blog for this.
  5. The BIM Manager should use the “Purge All Unused” tool.
    • Why not create seed projects that the team can open, browse and copy elements from?
  6. Export Families to review and audit. Use “Save As / Library / Family”. This tool will add all the families from the project to the folder you select. Careful, this could take a while. Don’t drop them on your or your client’s desktop. ;-). Note any warnings and the family name if any errors occur. The warning will pop up and interrupt the Save As process. The Status Bar will have the name of the Family, Revit is exporting.
  7. Check that the worksets are being utilized properly.
    • I create a 3D view for each workset in the project. I then isolate the workset in each view. This allows me to review the project and ensure elements are on the right Workset.
    • I’ve seen elements on the Shared Level and Grid workset. How did that happen?
    • Be sure to create worksets for links and to utilize the opportunity to close worksets when creating new locals.
    • I recommend we use worksets to allow a local user to close the worksets they do not need to be loaded in their local file. Experience has proven this is an enormous opportunity to increase project performance.
  8. Check and resolve all Warnings.
    • Easier said than done. It’s best to address every warning as it happens. This should be an ongoing effort from the start of any project.
    • Microsol Resources offers a Revit Model Health Check service. Contact me for more info.
  9. At this point the Backup and Revit Temp folders related to the Central Model are useless at this point, they should be deleted.
    • .slog file, Worksharing Log File, is part of the _backup folder for the central model. It is found inside the folder Central_File_backup where the Central_File.rvt is located. This file contains information on the Sync with central progress, element borrowing, and users accessing the central file.
    • An example of a permission issue is when someone can’t edit the element because it is being edited by another user, but this user is not currently in the model.
    • The Revit SLOG file could be corrupt and will be re-created after performing these maintenance steps.
    • The backup folder is useful only when the project is in production and the team wants to Roll Back the project to a previous date, indication in the project history.
    • BIM 360 does not have a .slog file.
  10. Once the backup and Revit folders are deleted the BIM Manager can create a new Central Model by performing a save-as and choosing “Make this a Central Model after save” in the options dialog with “Compact Central” checked. While in this dialog always ensure the following
    • Indicate the “Maximum” number of backups. 20 is the default. These backups are usable when the team chooses to Roll Back the project. Not my first choice.
    • Choose the option of “Specify” under the section called “Open Workset Default” This gives each local user the option to close worksets when creating their new local file.
    • When we close DWG Links worksets we see an enormous performance benefit.
    • Choose a simple drafting view, “Bulletin Board” as the source for the “Thumbnail Preview” section.
    • Lazy parsing plays a role in this performance gain.
      “Lazy parsing” means that the data for each element isn’t converted until it is actually needed. The main uses for the data in an element are to display that element or to regenerate it when there are changes to other elements it depends on. Thanks to Irwin Jungreis and their forum contributions
  11. All users can now Create new Local files.
BIM 360 Model Maintenance

When a project in the cloud, in BIM 360, is seeing signs of possible corruption we should use the same maintenance procedures on these files as well. First, one would need to take it down, or copy the RVT to a local computer and preform these maintenance procedures. But we shouldn’t just copy and paste.

There are many instances of the model in the BIM 360 project. We have the version we open and edit while using Revit. We have the published version in BIM 360 Document Management, which is viewable when using the browser via docs.b360.autodesk.com. We even have copies of the file in various shared folders or even within coordination spaces.

Because it is sometimes difficult to determine what has been published most recently and what sets are included. It is our recommendation to open the RVT via Revit.  Open your model, Sync with Central, and Relinquish all editable items.  use the “Save As” function to save a copy of the file to your desktop or the local machine. Make sure you check the options in the File Save As dialog, choose “make this a central file after save”.  Perform maintenance starting from step #3 above.

Let me know your thoughts on this process. You may have another tip I can add to this resource.

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Top 12 Tips for Utilizing Revit Groups

Here are my top 12 tips for utilizing Revit groups. Ten was just not enough. In my opinion, groups can be the most abused tool in the toolbox. So why do we use them? 

Well, it seems to be a no brainer. Like in AutoCAD, architects, MEP engineers, and construction professionals create groups of repetitive and yet still quantifiable elements as if they were individual elements. Modify one instance of the group, and Revit will update every instance of that group in the entire project. One can even exclude an element from a group instance to make an exception.  Select the group, hover over an element in the group, and tab in until the specific element is highlighted, then left-click. That element now displays a symbol, which will allow us to exclude it from this group instance. See the image below. This does not make this group a new group. Pretty cool.

Of course, groups can be made in CAD, but in Revit, groups are broken down into model groups and detail groups. Detail groups for annotation, text, and detail items like 2-dimensional detail components. Think clips, brick, or flashing. These groups can be exported out to the library and imported as groups into other projects. Model groups typically hold Revit families. The two types of elements, detail and model, cannot be created in the same group. They are managed separately.  Let’s now discuss the methods of creating groups and the various benefits of doing so. 

How to Group in Revit

Create a group by selecting elements or existing groups and using the Create Group tool.

  1. In a project view, select the desired elements or existing groups you want in the group.
  2. Click Modify | Multi-Select tabCreate panel (Create Group).
    Note: If you have only selected one element type, the respective Modify | <Element> tab displays instead of the Multi-Select tab.
  3. In the Create Group dialog, enter a name for the group.
    Note: The name of this dialog will vary depending on the types of elements you selected.
  4. If you want to open the group in the group editor, select Open in Group Editor.
    The group editor allows you to add or remove elements from a group, attach detail groups (for model groups), and view group properties.
  5. Click OK.


Over the years, Autodesk and the Building Information Modeling (BIM) team have improved this excellent tool. This process to edit a group is as simple as a double click, but they have not made groups more flexible. If we create a group the wrong way, Revit gets upset. You don’t want to see Revit upset. In actuality, Revit gets confused. The main problems occur when groups contain elements that are constrained outside the group. In the simplest form, if one were to create a group of elements, including a door, the wall where the door is hosted would need to be within that group. The wall could have a top constraint that does not apply to all instances. It is also common to create groups for casework that rely on the walls for placement, but the walls are not part of the group. In class, you may have heard me say, groups should be “self-centered.” These types of constraints can also cause problems in Design Options.

That being said, yes, there are restrictions that one should be aware of when implementing the use of groups throughout a big AEC project.

Here are 12 Top Most Useful Tips on How to Utilize Revit Groups

  1. Put elements and their hosts in the same group.
  2. Ensure all elements in the group are hosted to the same level.
    • Some elements may not behave correctly—line-based families, for instance.
  3. Don’t constrain elements outside the group. There are many kinds of constraints.
    • Un-constrain the elements within the group, so they are no longer tied to elements outside the group.
  4. Large numbers of elements in a group will hinder performance and possibly cause corruption.
  5. It is better to have many small groups than a few large groups.
  6. Don’t nest Groups. Don’t have groups inside groups.
  7. If you see a warning asking you to fix the groups, don’t.
    • Fixing the group doesn’t fix the group. It explodes it or creates a new group that is no longer referenced to the first group.
  8. Name groups correctly. Don’t make copies of groups called Group1.
  9. Although we are now able to mirror groups, some elements with constraints still cause problems when mirrored. Ceilings in groups get confused when mirrored.
  10. Take ownership of the group type workset when editing.
    • All elements in a group reside on the group instance workset.
    • Be aware of the ownership of type properties.
  11. Be cautious putting floors or stairs in groups. Don’t lock the sketch lines to other objects.
  12. Groups can be used to distribute elements and then can be ungrouped.
    • For instance, we use the array command to make multiple copies. The default option is to “Group and Associate.” Ungroup them when complete.


Benefits of Revit Groups

We all should be considering what content from our successful Revit projects can be shared with the office and used in current and future projects. In the past, the Revit group had its file format. I’m dating myself now. Currently, Revit saves model elements as RVTs or Revit project files. These files can be loaded into the project and placed as groups. In the family environment, groups can be saved as RFA, Revit family files.

You can save a group as a project file (RVT) if you work on a project or a family file (RFA) if you are working in the Family Editor.

  1. Click File tab Save AsLibrary (Group).
  2. By default, the File name text box displays “Same as the group name.” If you accept this name, Revit saves the file with the same name as the group. So a group called Group 5 saves as Group 5.rvt (or Group 5.rfa). If desired, you can change this name.
  3. If your project has multiple groups, select the appropriate group from the Group to Save drop-down.
  4. Specify whether to Include attached detail groups as views.
  5. Click Save.



Revit’s group tools and functionalities are powerful if used carefully and thoughtfully. Getting the right training and having an organized approach is everything. Go forth and make groups as long as you and the team have a plan in place. 

In a previous post, I discussed, “What Causes Revit Data Corruption?” and some model maintenance suggestions, “Revit Project Maintenance Guidelines.” I hope you find this article and those listed here helpful. I welcome you to reach out with questions or comments anytime.

Credits: About Best Practices for Groups from Autodesk Knowledge Network; Best Practices with Revit Groups: Rule #1 by Sean D Burke


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