Max Verstappen led the pack out of the pits at the start of the one-hour session and he set the first place benchmark at 1m20.154s in his RB19 which was fitted with an aerodynamic load-measuring device.
He was quickly shuffled back in the standings as the rest of the drivers that had headed out when the track went live posted their opening times, with Bottas's 1m18.728s the best of the very limited bunch.
The running was then stopped after Alpine's Pierre Gasly came to a halt on the long run between Turns 7 and 8 due to a driveshaft issue.
Once his car was pushed behind the barriers as FP1's first five minutes closed out, the session did not get going again as expected.
Mercedes was so certain green flag conditions would soon return it sent Lewis Hamilton and George Russell to the end of the pitlane, but when they were held there for several minutes the Black Arrows mechanics had to rush down and wheel the cars back to their garages.
Mercedes said in a statement "Both cars headed to end of pit lane but then a problem in race control meant the circuit was not reopened while it is resolved".
It added: "This issue was only communicated when cars reached end of pit lane. So we have brought the cars back as they would have lost any useful tyre temperature."
At this point, nearly 20 minutes into FP1, the FIA formally communicated in its own statement that the session could not restart because CCTV cameras around the Montreal track were not working as expected and so the pitlane could not be reopened and the session resumed.
The FIA statement read: "The session restart has been delayed due to issues with the local CCTV infrastructure around the circuit.
"The local organisers are working to resolve the issue and until that time we can't restart for safety reasons."
The FP1 clock continued to count down per F1's rules and approaching the 40-minute mark the FIA issued another statement explanation.
This read: "The delay will be longer as the CCTV is not synced correctly and until the issue has been fixed we cannot run on track.
"This system is a local installation and they are continuing to work to resolve the problem.
"The clock will continue to run down on FP1 and the session won't be extended as there must be 2.5hrs between FP1 and FP2. We are looking at options to extend FP2."
With 10 minutes of FP1 remaining it was announced that the session would not be resumed, while the event stewards announced that FP2 will start 30 minutes earlier – at 4.30pm local time – and last 30 minutes longer.
The unusual end to FP1 followed problems with the event's electricity supply impacting the team's preparations for the session.
When the teams went to start heating the tyres required in FP1, the added strain on the electricity supply, which has to be adapted from 60hz to 50hz for the equipment the teams have designed based on European standards, meant the power supply cut out.
Teams were forced to use generators to heat their tyres, but as the CCTV system uses a different power system the two problems are in theory unrelated.
In the order behind Bottas, came Aston Martin pair Lance Stroll and Fernando Alonso, then Sergio Perez and Verstappen.
Oscar Piastri (McLaren), Haas pair Kevin Magnussen and Nico Hulkenberg, Zhou Guanyu in the other Alfa and Ferrari's Carlos Sainz rounded out the top 10.
Behind came Charles Leclerc and Nyck de Vries as the only other drivers to set a lap time and the last drivers to reach a total of three laps.
Yuki Tsunoda, Lando Norris and Logan Sargeant had to abandon the first efforts due to the Gasly red flag, with Alex Albon doing just a single installation lap.
Esteban Ocon was not in his car when FP1 was first stopped due to his team-mate's issue as the team investigated a problem, while the Mercedes duo also never made it out on track.
| Cla | Driver | Chassis | Engine | Laps | Time | Gap | |
|---|---|---|---|---|---|---|---|
| 1 |
 Valtteri Bottas |
 |
Alfa Romeo | Ferrari | 3 | 1'18.728 | |
| 2 |
 Lance Stroll |
 |
Aston Martin | Mercedes | 3 | 1'19.175 | 0.447 |
| 3 |
 Fernando Alonso |
 |
Aston Martin | Mercedes | 3 | 1'19.807 | 1.079 |
| 4 |
 Sergio Perez |
 |
Red Bull | Red Bull | 3 | 1'20.154 | 1.426 |
| 5 |
 Max Verstappen |
 |
Red Bull | Red Bull | 3 | 1'20.231 | 1.503 |
| 6 |
 Oscar Piastri |
 |
McLaren | Mercedes | 3 | 1'21.496 | 2.768 |
| 7 |
 Kevin Magnussen |
 |
Haas | Ferrari | 3 | 1'24.045 | 5.317 |
| 8 |
 Nico Hulkenberg |
 |
Haas | Ferrari | 3 | 1'24.336 | 5.608 |
| 9 |
 Zhou Guanyu |
 |
Alfa Romeo | Ferrari | 3 | 1'24.961 | 6.233 |
| 10 |
Carlos Sainz |
 |
Ferrari | Ferrari | 3 | 1'25.991 | 7.263 |
| 11 |
 Charles Leclerc |
 |
Ferrari | Ferrari | 3 | 1'26.809 | 8.081 |
| 12 |
Nyck de Vries |
 |
AlphaTauri | Red Bull | 3 | 1'32.274 | 13.546 |
| 13 |
 Yuki Tsunoda |
 |
AlphaTauri | Red Bull | 2 | ||
| 14 |
 Lando Norris |
|
McLaren | Mercedes | 2 | ||
| 15 |
 Pierre Gasly |
 |
Alpine | Renault | 1 | ||
| 16 |
 Alex Albon |
 |
Williams | Mercedes | 1 | ||
| 17 |
 Logan Sargeant |
 |
Williams | Mercedes | 2 | ||
| 18 |
Esteban Ocon |
 |
Alpine | Renault | 0 | ||
| 19 |
Lewis Hamilton |
 |
Mercedes | Mercedes | 0 | ||
| 20 |
George Russell |
|
Mercedes | Mercedes | 0 | ||
| View full results | |||||||
