error showed up when I clicked Build >> Android App (APK):

[ReadBuildInfo] Starting Task
[ReadBuildInfo] Task succeeded in 0.007 seconds
[LoadComponentInfo] Starting Task
[LoadComponentInfo] INFO: Generating assets...
[LoadComponentInfo] Component assets needed, n = 0
[LoadComponentInfo] INFO: Generating activities...
[LoadComponentInfo] Component activities needed, n = 1
[LoadComponentInfo] Component activity metadata needed, n = 0
[LoadComponentInfo] INFO: Generating broadcast receivers...
[LoadComponentInfo] INFO: Generating libraries...
[LoadComponentInfo] Libraries needed, n = 5
[LoadComponentInfo] Component metadata needed, n = 0
[LoadComponentInfo] INFO: Generating Android minimum SDK...
[LoadComponentInfo] INFO: Generating native libraries...
[LoadComponentInfo] Native Libraries needed, n = 0
[LoadComponentInfo] INFO: Generating permissions...
[LoadComponentInfo] usesLocation = False
[LoadComponentInfo] Permissions needed, n = 7
[LoadComponentInfo] Component xmls needed, n = 0
[LoadComponentInfo] Component features needed, n = 0
[LoadComponentInfo] INFO: Generating component broadcast receivers...
[LoadComponentInfo] Task succeeded in 0.004 seconds
[PrepareAppIcon] Starting Task
[PrepareAppIcon] INFO: Creating mipmap dirs...
[PrepareAppIcon] INFO: Generating icons...
[PrepareAppIcon] Generating icons for mipmap-mdpi
[PrepareAppIcon] Generating icons for mipmap-hdpi
[PrepareAppIcon] Generating icons for mipmap-xhdpi
[PrepareAppIcon] Generating icons for mipmap-xxhdpi
[PrepareAppIcon] Generating icons for mipmap-xxxhdpi
[PrepareAppIcon] Task succeeded in 1.064 seconds
[XmlConfig] Starting Task
[XmlConfig] INFO: Creating animation xml
[XmlConfig] Creating zoom_enter.xml
[XmlConfig] Creating fadeout.xml
[XmlConfig] Creating slide_v_exit.xml
[XmlConfig] Creating fadein.xml
[XmlConfig] Creating zoom_exit.xml
[XmlConfig] Creating slide_v_enter.xml
[XmlConfig] Creating zoom_exit_reverse.xml
[XmlConfig] Creating slide_v_enter_reverse.xml
[XmlConfig] Creating zoom_enter_reverse.xml
[XmlConfig] Creating slide_enter_reverse.xml
[XmlConfig] Creating slide_exit.xml
[XmlConfig] Creating hold.xml
[XmlConfig] Creating slide_enter.xml
[XmlConfig] Creating slide_v_exit_reverse.xml
[XmlConfig] Creating slide_exit_reverse.xml
[XmlConfig] INFO: Creating style xml
[XmlConfig] INFO: Creating provider_path xml
[XmlConfig] INFO: Creating network_security_config xml
[XmlConfig] INFO: Generating adaptive icon file
[XmlConfig] INFO: Generating round adaptive icon file
[XmlConfig] INFO: Generating adaptive icon background file
[XmlConfig] Task succeeded in 0.007 seconds
[CreateManifest] Starting Task
[CreateManifest] INFO: Reading project specs...
[CreateManifest] VCode: 1
[CreateManifest] VName: 1.0
[CreateManifest] Min SDK 14
[CreateManifest] INFO: Writing screen 'appinventor.ai_fntw1337.grib.Screen4'
[CreateManifest] INFO: Writing screen 'appinventor.ai_fntw1337.grib.ZT15'
[CreateManifest] Task errored

If these don't help, export and post the aia file here.

grib_Screen_ 2.aia (4.6 MB)

I had to go into Project Properties and remove a trailing blank from the app name to get it to build.

grib_Screen______1.aia (4.6 MB)

The code server did not like your Project name, so it applied its own name.

By the way, you are not reusing Screens enough.
You have exceeded the safe limit of screens, and they appear to be similar in design.

See the first two links at