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Web Preview Never Loads (& New console errors)
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Awesomeosep
Hello all,
Yesterday we noticed that the web preview for this app would no longer load. and would just display the basic spinner endlessly. We checked the potential causes listed on docs.appgyver.com/troubleshooting-faq and tested with several devices, browsers, and repeatedly tried clearing the cache but nothing worked. We decided to roll back a couple of versions and this actually solved the problem.
However, today (12/21), the web preview for the same app is presenting this bug once again. We noticed two new errors in the JS console. These don't present in other apps, so we suspect they may be related to this problem:
*Failed to load resource: net::ERR_INCOMPLETE_CHUNKED_ENCODING
*Uncaught (in promise) Type Error: Failed to fetch
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The web previews of other apps seem to work, but this app does not. We tried the "solution" that had worked yesterday of doing a rolling back (to the same point we had yesterday). But this time the older version did NOT work, so we reverted back to the latest version of the app. We instead attempted to duplicate the app using Composer's new built-in duplication feature (which is awesome by-the-way :D) but the duplicate's preview did not work either. (Duplicate 1 App ID: 323608)
Because this duplicate did not work, we decided to make a duplicate of the version from 2 days ago. We made a duplicate of this version (Duplicate 2 App ID: 323605). But to my surprise, this duplicate works.
We could potentially continue development with this (working) duplicate and just recreate the changes we've made since that version.
But as this is the SECOND time we are encountering this error, we would like to resolve the error before continuing development in case it happens again. Ideally, we would also like to continue building in this main app. Could the Appgyver Team help us resolve this issue?
timo.kapanen@appgyver.com, sorry for mentioning you, but would you mind having a look at this for us? :)
We're very close to launching our first app in Appgyver (which we believe is an amazing platform and community). I can't wait to see what improvements and growth this platform sees in the next year. Thanks, Awesomeosep
More Details:
- Client Runtime Version: 3.3.3
- Main App ID: 218625; Duplicate 1 App ID: 323608; Duplicate 2 App ID: 323605;
- Page: No page in the app ever seems to load
- Build Type: Preview

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Timo Kapanen
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Timo Kapanen
Hi Awesomeosep, the main app is restored and we continue to study the actual issue. Sorry for the inconvenience and delay this might have caused. Best Regards, Timo Kapanen
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Awesomeosep
Hey Timo Kapanen,
When I logged in this morning and saw your message, I immediately checked the preview and it was working perfectly.
I hadn't had a chance to reply to your message until now, but as I was writing this, we tested again and the same error seems to be occuring again.
We haven't edited or saved the app since then, so this seems very strange. 🤔 Thanks, Awesomeosep
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Timo Kapanen
Awesomeosep: our developer is studying the issue, no break through yet. He will continue tomorrow and is hopefully able to find solution prior the holidays starting. Going forward, you might want to improve robustness in authentication page, i.e. adding hide spinner flow to some of the 'branches' in that page. Currently you could end up to infinite spinner state. Anyway, the issue we currently see is not caused by that as the app is not even reaching that page but fails in app opening. Best Regards, Timo Kapanen
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Timo Kapanen
Hi Awesomeosep, we have continued to study this but unfortunately there is no solution yet. The app is actually opening if you wait in worst case several minutes. We continue to analyze what is the bottleneck in this particular app opening. Best Regard, Timo Kapanen
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Awesomeosep
Hi Timo Kapanen:
Sorry for not replying in a while. We wanted to update you with some interesting discoveries that may help explain the preview app issue we've been experiencing. We observed most of these last week around and before December 24th.
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▶ We found that when we would insert Firebase data resource nodes, the preview seemed to break. Based on this observation, we tested the following:
• We would add a Firebase create record node and the preview would break.
• We rolled back which fixed the error and instead added a client-side database create-record node. With only the local DB create-record node, the preview worked.
• We attempted connecting a Firebase create record node to the client-side database node we had added previously. With both the local and Firebase nodes attached, the preview continued working. 🤔
• We wondered if the error had to do with filters in get_record_collection requests using the Firebase connector. We repeatedly tested and determined that filters did not seem to affect the error.
• We also noted that none of the issues seemed to affect new or blank apps.
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▶ Another theory we had was that the error was related to the 8 updates in the Component Marketplace. We suspected this may be the reason, as one of the updates was of the Initialize Firebase flow function. We hadn’t had time to go through and update them as they were relatively new.
• So, we used an existing duplicate that had stopped working and updated all of the suggested updates. This fixed the preview so we then tested this on the main app.
• This fix worked for a while, but eventually, the main app stopped working once again.
•We then rolled it back to before we made the updates, and re-updated the components. This version worked and we also found that rolling back (forward?) to the most recent version after doing this would also work. 😀
▶ This gave us a temporary solution that we managed to repeat several times when it would break.
Throughout this testing, the error would periodically occur at random times and the previews of the duplicate of the working main app worked most of the time but occasionally would not. 🤔
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We had paused development after 12/24 when the preview was still working fine. However, when we checked the preview yesterday, we realized that it had stopped working again yet we hadn’t modified the app in between.
Now, none of the duplicates we had made last week (including the stable version that has been working the entire time) are working anymore and all report the same error. The error is beginning to seem somewhat random and I don't know if any of this will be helpful... 😅
Happy New Year, 🎉
Awesomeosep
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Timo Kapanen
Hi Awesomeosep and thanks for your update and sharing your finding, I'll pass these to our development team. Our developer has also done some intense study on this, sorry for not giving you update. Here are his findings:
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The endless spinner is not endless, the app will eventually open when the transdolan manages to do its job within 120 seconds. Transdolan is slow because the dolan parser is slow. The main two reasons based on our analysis for slow parsing are:
- Complex formulas
- Lot of flows
It is very possible that we could optimize our side but for now my recommendations are the following:
- Try to simplify the formulas
- Try to simplify the flows and remove the ones that are not needed
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Hopefully these will help you also to make again progress. Happy New Year 2022!
Best Regards, Timo Kapanen
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Awesomeosep
Today (12/30/2021), when testing the main app, the preview did eventually work (after a few unsuccessful tries). You seem to be correct that the number of transdolan requests appears to reach about 200 (requests seem to occur every second or so) when the app does not work.
After discovering the app was working, we created a new node with a formula, and after this change, the preview stopped working and would no longer load. We tried the “solution” we had found rolling back to previous versions, including the one which had worked earlier today. Unfortunately, this did not work. 🙁
We plan to go through large formulas and nodes in the app and simplify them… (We have a lot of these) However, we have another app that should have WAY more of these nodes & formulas but does not seem to be experiencing this issue… 🤔
Thanks,
Awesomeosep
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Timo Kapanen
Awesomeosep: getting back to this one. We have studied your app in our test environment and were able to do some optimizations for the parsing such that app opens roughly in one minute. The earlier suggested recommendations with formulas and flows are still valid, anyway the app seems to open now in preview. We expect to be able to publish the changes later in the week as part of preview version 3.4 releasing to production. Thanks you for your patience and hopefully this unblocks your development effort for this app. Best Regards, Timo Kapanen
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Timo Kapanen
Hi Awesomeosep, we published a new parser version today. I checked that the app is opening even it takes awhile (little over one minute). Best Regards, Timo Kapanen
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Awesomeosep
Hey Timo Kapanen, Thank you so much... We've continued simplifying things where we can, but the preview's definitely working again!
Thanks again for all your hard work,
Awesomeosep
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Timo Kapanen
Awesomeosep: great to hear that you are able to continue your work. I close this ticket as the immediate issue is solved even we also continue to work on further profiling and optimizations of parsing. Best Regards, Timo Kapanen
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Timo Kapanen
Awesomeosep: just to let you know that we have gone through another round of parsing optimisation. Your app should be opening faster now. Best Regards, Timo Kapanen
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Timo Kapanen
under review
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Timo Kapanen
Hi Awesomeosep and thanks for your report. And sorry, I think I made a bad mistake and deleted the main app while my purpose was to make another copy of it to study it. We will restore the app but it takes a short while. Deeply sorry about this. Best Regards, Timo