Image: CNET/CBS Interactive

Users of Google's latest mobile operating system, Android 5.0 Lollipop, are warning others not to immediately upgrade, after experiencing broken apps, repeated crashes, and device slowdowns.

Many are reporting early issues with calling, failing Wi-Fi connectivity and sound quality — in some cases, audio fails to work altogether.

But a more pressing issue emerged: Apps built with Adobe Air have in many cases been removed from users' Nexus devices, and cannot be reinstalled.

The fifth major version of Android, dubbed "Lollipop" after Google's candy-based naming scheme, was widely lauded in a positive review by sister-site CNET. It lands with a number of improved features, including a new user interface and experience, and a consistent design across the board — from smartphones to tablets, and newer devices, such as wearables.

"Unusable"

The Lollipop update has been hit with some harsh criticism by its users since it first landed in their hands, despite strong feedback from the tech community when it was first announced earlier this year.

Users have said they "regret" the over-the-air download, saying the older Nexus 7 tablet is "laggy, restarts, and crashes randomly." In some cases, apps were not responding.

"The whole tablet experience is ruined," a user wrote.

Android user Cristian Alejandro Chavez Lopez said: "That's the word to describe it: unusable."

A number of people on Adobe's forums have complained that installing Air apps would see a non-descript error message, "-505".

Image: Adobe

But, according to a post by program manager Chris Campbell, the issue has been "escalated" to Google," seemingly pointing the finger at the search giant rather than in its own camp.

Campbell said the company had not been aware of what he described it as a "critical" bug before November 18.

But there was confusion over exactly who knew what.

App developers for Bonza, one of the affected apps, investigated the problem, one Google developer forum post said.

User "PaddyLandau" said in the post that Google said that the "-505" error is "a known issue for apps running Adobe Air on Android 5.0."

However, Campbell was quick to deny that Adobe was aware of this bug, and contrary to reports "were not working with Google on a fix."

He added that the company was not able to reproduce the problems internally.

"We're going to expand our testing and engineering will be canvassing the forum posts and bug reports for additional clues," he said.

"A paperweight"

Although the software is only available on a limited number of devices, thanks in part to the cellular carriers withholding the software until device testing is complete, many of the issues appear to be related to Google's own branded smartphones and tablets.

Android Lollipop is currently available for Google's range of Nexus phones and tablets, including the new Nexus 6 "phablet" and Nexus 9 tablet, which were released last month.

Google Nexus owners can download the factory images for their devices for installing, or download it over-the-air on Nexus 7 devices — which, based on the forums, appear to be having the most problems.

Many on Google's support forums have contributed to a "how to restore" post, detailing how to revert back to Android 4.4 KitKat, because according to one user, Lollipop has turned their Nexus 7 into "nothing more than a paperweight."

We reached out to Google for comment, but did not hear back at the time of writing. Any updates, and we'll include them here.