Build Errors

There are two types of build errors that happen; they are yellow warnings and red alerts. You'll see the warnings and alerts in the left-hand column of the Xcode window.

Yellow warnings do not cause the build to fail, those are just warnings. Occasionally, a Loop version may have some minor discrepancies that cause a yellow alert...ignore those. Do not try to do anything to fix those...leave them alone.

Red error alerts will have to be resolved before you can successfully build the Loop app. The steps below explain how to resolve them based on the messages you are seeing.

Start with the obvious error causes

Before you start trying to resolve your red errors...start with the most obvious things that can cause a red error message:

  1. DO NOT USE BETA VERSIONS If you are using an iOS beta version or an Xcode beta version, your Loop will not build. If you have Xcode beta, uninstall it and get regular Xcode. If you have iOS beta on your iPhone, you will need to restore your iPhone entirely. You can restore to either (1) the last non-beta backup version you saved or (2) restore as a new iPhone (default settings). Yes, deleting iOS beta is a don't install it in the first place.

  2. Did you check for updates?

    Minimum Versions

    If you are building for Omnipod Loop, Loop dev, or have iOS 12.2 installed, make sure you have macOS 10.14.3 (Mojave) and Xcode 10.2 at a minimum. You will not be able to build for those without the minimum updates.

  3. Get a fresh download of Loop code, don't just recycle an old download that you built with a long time ago. That old version may not be compatible with new iOS and new Xcode versions.

  4. If you are using a free developer account, you need to have finished the code customizations to remove Siri capabilities.

Posting for help

STOP!! Read this section! Important!

Before you post in Zulipchat or Looped Group asking for help with build errors, do your work first. The build errors listed below (and the obvious checks listed above) are very successful IF PEOPLE READ THIS PAGE. The volunteer group of people answering questions in Looped and Zulipchat would love to spend more time on improving Loop in other ways than answering build error questions that can be answered by using this page as a first step.

Therefore, first use the error topics (listed in sections below) to try to resolve your build error yourself. Then, if you need to post for help because this page did not fix your problem, you'll need to include information with the post so we (the troubleshooters) know you read this page and where you are in your troubleshooting attempts

Include in your post:

Helpful tip #1: Shift-Command-4 will give you a little screenshot tool that you can click-and-drag to highlight the area you'd like to screenshot. When you release the drag, the screenshot will save to your desktop so you can include it in your post. Phone photos of your computer screen won't likely be of sufficient clarity to read the needed information.

Helpful tip #2: When taking screenshots for a post, include the whole Xcode window. Don't zoom in on any one area. There is information in all parts of the Xcode window that are helpful to the troubleshooters, so it saves time to see the whole Xcode window at once.

Find your error message(s)

To begin fixing the error (assuming you didn't have one of the obvious issues listed above), the key is to (1) READ THE ERROR MESSAGE and then (2) FIND YOUR MESSAGE IN ONE OF THE TOPICS BELOW.

Here's a super tip: Merely seeing the "exit code" in Xcode is not enough information to discern what error is causing your build to fail. Look at the detailed message to really help guide your search for the matching solution.

Notice how in the screenshots in the topics below, there are red circles highlighting certain error messages? Read your error messages similar to where those red circles are in the screenshots below. Once you find your error message (hint: not "exit code"), you can either:

For example, if you see "Invalid active developer path (/Library/Developer/CommandLineTools)" in your error message, use the search tool in LoopDocs with simply "invalid active". You will get a couple of links and one is the Command Line Tools fix for that error message. Click on the link and you'll find your solution.

No such module 'LoopKit'

If you see a Cartfile failure and several other red errors (in particular saying there is "no such module 'LoopKit'"), double click on the Cartfile error message. If it says that the build failed in one of the schemes, as shown in the screenshot below, then you need to open the Terminal app. You will use the command cd ~/downloads/loop-master && carthage update. NOTE: YOU MAY HAVE TO CHANGE THE COMMAND SLIGHTLY. If your loop folder isn't named loop-master and instead is loop-master-2 or loop-dev or some other folder name...change the command to match your folder's actual name.

Carthage update will take about 15-25 minutes to run successfully. A successful carthage update will look like the following:

Once carthage update has run successfully, you can return to Xcode and press the build button again. Your project should build successfully.

If your carthage update fails, try opening the Terminal app and running these commands to clear out your carthage cache and saved derived data in Xcode:

rm -rf ~/Library/Caches/org.carthage.CarthageKit and rm -rf ~/Library/Developer/Xcode/DerivedData

After running those commands, retry the cd ~/downloads/loop-master && carthage update (remembering to update the name of your Loop download folder, as needed).

Carthage version outdated

If you see a message about updating carthage version, open Terminal app and enter the following command brew update && brew upgrade carthage

Not using Xcode 10.2

Error message: The error message may change over time and Xcode versions...currently if you use iOS 12.2, Omnipod-testing branch, or dev branch and have not updated to macOS 10.14.3 and Xcode 10.2 at a minimum, you will receive the following errors when you try to build:

Solution: You will need to update you macOS and then use your computer's App Store to install the Xcode app update.

Missing Command Line Tools

Error message: "Invalid active developer path (/Library/Developer/CommandLineTools)" or "unable to find utility "xcodebuild", not a developer tool or in PATH"

Solution: Go to your Xcode preferences and under the Locations tab, select "Xcode 10.1" in the dropdown menu for Command Line Tools.

Pending Certificate Request

Error message: "You already have a current iOS Development certificate or a pending certificate request."

Solution: This error message has just recently started to appear for some new Loop builders. To resolve the issue, please log in to your Developer account at and then click on "Certificates, Identifiers & Profiles". Under that screen, you will see "Development" under the "Certificates" section in the column on the left. You will need to click on the certificates, and choose to "revoke" from the options that show after you click on the certificate. Confirm the warning message that will appear asking "Do you want to revoke the certificate?"

After you do that, return to Xcode and open up Xcode preferences. Under the Accounts section of Preferences, click on the minus sign to delete your Apple ID.

Re-enter your Apple ID (yes...add that account right back that you literally just deleted), return to your Loop's target signing areas in Xcode and your error message should have resolved itself now as a new certificate will have been issued and a provisioning profile should have been created automatically.

For double measure, you can verify that the iOS development certificates are all in good working order by clicking on your "Manage Certificates" in your Xcode Preferences, Accounts and viewing the iOS development Certificates. You should have one for your account that has a clean status similar to the screenshot below.

Command CodeSign failed

Error message: "errSecInternalComponent, Command CodeSign failed with a nonzero exit code"

Solution: This error message is likely due to inadvertently saying "no" to allowing Keychain Access or changing your computer or AppleID password. Regardless, the solution is as follows:

  1. Close Xcode
  2. Open your Keychain Access application (found in Applications within the Utilities folder, similar to where Terminal app is found)
  3. In the upper left corner of keychain access, make sure you have the keychain login highlighted and then click the large lock icon above the keychains area (High Sierra users) or right-click the lock next to the login (Mojave macOS users). Click the lock closed, and then click the lock to open it again. You will be prompted for a password. Enter your computer admin password. Close Keychain Access app.

  1. Open your Loop project again in Xcode.
  2. In the main Xcode menu (grey menu bar at the very top of your Apple display area), select the word Product and then select the option for Clean. (keyboard shortcut is shift-command-k)
  3. Now try rebuilding your Loop app. If you ever get prompted again to allow Xcode access to Keychain, make sure to Always Allow.

Developer License Update

Error message: "The Apple Developer Program License Agreement has been updated, In order to access certain membership resources, you must accept the latest license agreement."

Solution: You'll need to log onto your developer account at and accept the latest license agreement.

Unrecognized arguments: --cache-builds

Error message: "Unrecognized arguments: --cache-builds"

Solution: Please open your Terminal app found in the Applications>>Utilities folder and then enter /usr/bin/ruby -e "$(curl -fsSL" Confirm installation by pressing enter, and then typing in your computer password. When the installation finishes, use the command brew link --overwrite carthage. After those two steps, you can close out Terminal app, return to Xcode and press the build/play button again.

Abort with Payload

Error message: "Abort with payload" Your app will only open briefly with a white screen and then close, if you build with this error.

Solution: This error message is caused by either

  1. Saving Loop download folder into an iCloud mapped drive, or
  2. Having a space in the name of your Loop download folder.

Rename the folder to have no spaces and/or move it back to the Downloads folder, then rebuild.

Apple Watch: Loop app not appearing

Error: Apple watch app is not appearing.

Solution: Usually because you have not updated to watchOS prior to when you built Loop, or you didn't have your Apple watch paired at the time of building Loop. Don't forget to open the iPhone's Watch app, select My Watch tab on the bottom left, scroll all the way down, and click Install for the Loop app listed at the very bottom under "available apps".

Apple Watch: Loop app not installing

Error: The Loop app appears on the list of apps available to install on the watch, but when you press "install", and it goes through the animation of filling in the circle while it's installing, but then at the end it just toggles back to saying "INSTALL".

Solution: Plug your iPhone into the computer and start Xcode. On your watch, look for a prompt that says "Trust this computer". Scroll down on the watch face and select the "Trust" button.

Now we need to do one step before rebuilding Loop app again. Go to the top menu bar of Xcode and select "Clean Build Folder" from the Product menu option. Rebuild your Loop app.

For an unknown reason (developers are working on fixing it currently), if you do repeated builds in the same Loop project folder...the watch app can fail to install properly after the first build. Therefore, a simple "Clean Build Folder" will reset the folder back to new and you'll be able to install the watch after that fresh build.